Instead of re-installing, throw in the MDV2007 CD/DVD, and instead of selecting the "Install" option, select the "Upgrade" option.
That might fix the problem, it may not.
It's the only thing I can think to suggest.
Also, what I've taken to: If I'm tinkering around with Mandriva, and I make a change to a system file that renders my PC unable to boot, I always keep a copy of DSL (Damn Small Linux) around. It's bootable from the CD, and has been a life-line for me for a long time now.
It will automatically detect all your hardware settings and HD partitions. Use it to poke around in the files on your MDV install, and see it you can find anything that could provide an explanation to the problem.
reddazz:
I've heard on several occasions, also first-hand experience, Mandriva 2007 seems to disable that "Interactive boot" option, and it also doesn't grant you shell access if it stumbles upon a fatal boot error...you press Control-D like it says, and it just reboots on you.
It's a pretty shady bit of business.