( probably not a vista problem but put it here cause you never know)

When i start up my xps comp with vista it goes to the log on screen stays for 1 or 2 seconds then starts up again the only way i can get on is while its starting up is to press the off button.Then it goes to startup repair and after that i need to reinstall firefox every time it gets annoying.i cant try to install much because it just gets taken off the next time i startup repair.

Hi Ruggsymuggs

See if FF will function in safe mode with networking "keep tapping F8 at post - as soon as you start your PC" and try going on line, also have you installed any new software or hardware recently ?, do you use any full backup programs "eg" Acronis True Image that gives you the option to reinstall your OS as the time of backup ? have you tried system restore ? are your updates up to date and have you completed a full security scan of your PC ? lastly are all cables and components "eg" Ram in place correctly ?                                                                                                                                                                                                                                                                                                                                                                                                             

I'm beginning to think this maybe a boot problem, do you have the Vista installation CD ?, fixmbr necessary files are also in the WAIK package, available for free from the MS servers.

Thats good ! I think this may help if you rebuild the master boot record (even if don't fix your problem it will narrow the field of possibilities for your problem) and to save a lot of typing please see > Here