I have installed Ubuntu 10.04 on my laptop - ACER Aspire 7520 - but the screen is not clear and with fringed sides. Can anyone tell what is wrong? I have also installed Ubuntu 10.04 on "HP Pavilion Entertainment" with no problem.

Would you please link a screenshot? The description of the problem isn't very clear (I'm not sure a written description could make this issue clear ). My initial guess is that you have an incorrect refresh rate in your video settings. Also, posting your monitor specs and current video settings would be helpful.

I am new to Linux and not fomiliar with using this forum. I know how to take a screenshot, but not how to link it so you can see it.
How can I post "monitor specs" and "video settings"? I'll be very grateful to get this help, thank you.

There are several sites you can post a screenshot to and paste the link to the screenshot here on the forums. I usually use imageshack.

Monitor specs can usually be found on the manufacturers web site (you may have to do some digging )

Video settings can usually be found under System>Preferences or System>Administration under something like video, video settings or the like (I'd be more specific, but I don't use Ubuntu and I have third-party software from nvidia installed, which provides its own control panel for settings). Look for 'screen size' and 'refresh rate'. These settings need to match the specs from the manufacturer (especially refresh rate).

I have taken a screenshot of ny desktop, but when shown on my HP laptop the picture is OK without fringed sides.

Acer Aspire 7520 Laptop:
Technical Details

* AMD Athlon 64x2 Dual Core TK55
* Memory: 2x 512MB RAM
* Hard Drive: 80GB Hard Disk Drive
* Graphics Card: NVIDIA nFORCE 630M Chipset with NVIDIA GeForce 7000M
* Optical Drive: DVD SuperMulti, CD/DVD reader/writer for all types of CD/DVD discs
* Audio: Dolby Digital Live surround sound
* Connectivity: Wireless LANB/G, 4 x USB 2.0 Ports, 5 in 1 Card Reader
* Operating System: Windows Vista Premium:Additional Software: Acer Empowering Technology, Acer Arcade, Norton Internet Security Trial, Adobe Reader, NTI CD Maker
* Display Size: 17" WXGA TFT Display with Acer CrystalBrite technology

OK, I did some legwork for you. From what I could find on google, your monitor refresh rate should be set between 55Hz and 75Hz.

Please post the output of: This will tell us what driver is in use currently.

Tells us what video card you have (will also be shown in the lspci -k ouput)

Once we know what driver is in use, we can go from there!

NB: You can still look for your GUI video controls:

We'll need to know what refresh rate it is set to, and possibly need to change it.

Output of lspci -k:
00:00.0 RAM memory: nVidia Corporation MCP67 Memory Controller (rev a2)
00:01.0 ISA bridge: nVidia Corporation MCP67 ISA Bridge (rev a2)
00:01.1 SMBus: nVidia Corporation MCP67 SMBus (rev a2)
Kernel driver in use: nForce2_smbus
Kernel modules: i2c-nforce2
00:01.2 RAM memory: nVidia Corporation MCP67 Memory Controller (rev a2)
00:01.3 Co-processor: nVidia Corporation MCP67 Co-processor (rev a2)
00:02.0 USB Controller: nVidia Corporation MCP67 OHCI USB 1.1 Controller (rev a2)
Kernel driver in use: ohci_hcd
00:02.1 USB Controller: nVidia Corporation MCP67 EHCI USB 2.0 Controller (rev a2)
Kernel driver in use: ehci_hcd
00:04.0 USB Controller: nVidia Corporation MCP67 OHCI USB 1.1 Controller (rev a2)
Kernel driver in use: ohci_hcd
00:04.1 USB Controller: nVidia Corporation MCP67 EHCI USB 2.0 Controller (rev a2)
Kernel driver in use: ehci_hcd
00:06.0 IDE interface: nVidia Corporation MCP67 IDE Controller (rev a1)
Kernel driver in use: pata_amd
Kernel modules: pata_amd
00:07.0 Audio device: nVidia Corporation MCP67 High Definition Audio (rev a1)
Kernel driver in use: HDA Intel
Kernel modules: snd-hda-intel
00:08.0 PCI bridge: nVidia Corporation MCP67 PCI Bridge (rev a2)
00:09.0 IDE interface: nVidia Corporation MCP67 AHCI Controller (rev a2)
Kernel driver in use: ahci
Kernel modules: ahci
00:0a.0 Ethernet controller: nVidia Corporation MCP67 Ethernet (rev a2)
Kernel driver in use: forcedeth
Kernel modules: forcedeth
00:0c.0 PCI bridge: nVidia Corporation MCP67 PCI Express Bridge (rev a2)
Kernel driver in use: pcieport
Kernel modules: shpchp
00:0d.0 PCI bridge: nVidia Corporation MCP67 PCI Express Bridge (rev a2)
Kernel driver in use: pcieport
Kernel modules: shpchp
00:12.0 VGA compatible controller: nVidia Corporation C67 [GeForce 7000M / nForce 610M] (rev a2)
Kernel driver in use: nouveau
Kernel modules: nvidiafb, nouveau
00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
Kernel driver in use: k8temp
Kernel modules: k8temp
01:04.0 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller (rev 05)
Kernel driver in use: ohci1394
Kernel modules: firewire-ohci, ohci1394
01:04.1 SD Host controller: Ricoh Co Ltd R5C822 SD/SDIO/MMC/MS/MSPro Host Adapter (rev 22)
Kernel driver in use: sdhci-pci
Kernel modules: sdhci-pci
01:04.2 System peripheral: Ricoh Co Ltd R5C843 MMC Host Controller (rev 12)
Kernel driver in use: ricoh-mmc
Kernel modules: ricoh_mmc
01:04.3 System peripheral: Ricoh Co Ltd R5C592 Memory Stick Bus Host Adapter (rev 12)
01:04.4 System peripheral: Ricoh Co Ltd xD-Picture Card Controller (rev ff)
05:00.0 Ethernet controller: Atheros Communications Inc. AR5001 Wireless Network Adapter (rev 01)
Kernel driver in use: ath5k
Kernel modules: ath5k
ubuntu@ubuntu:~$

FYI: My laptop (an HP 9700) has a very similar chipset, with the nVidia C67 controler:With the FOSS nouveau driver, I had many problems. When I switched to the (propitiatory) nVidia driver, all the problems were immediately resolved.

I agree, you'll probably want to install the proprietary drivers at this point. I would follow this guide, and post back if you run into specific problems.

I'm running Debian Sid with a liquorix kernel, using the nouveau driver with a GEForce 8600M GT and had no video problems (that I've noticed yet). Odd, but....

EDIT: Until I installed the liquorix (2.6.34) kernel I always used the proprietary drivers with no problem. When I installed the newer kernel, I decided to give the nouveau driver a try, since it is supposed to support 3D acceleration. I haven't done any testing of the driver yet, but in day-to-day use it has served me fine so far.

I followed your advice and now everything work fine!
THANK YOU!