So far the Ultimate Boot CD for Windows has saved three PCs. I created one a couple of years back, when a PSU died and slightly mangled a hard drive in the process; with utilities on the UBCD I fixed the boot record and reverted Windows to a previous system restore point when it wouldn’t load (after recovering the system restore points from files chkdsk had recovered). Last year a friend had an almost identical problem, and once again the UBCD got us back to a previous system restore point. Yesterday another friend’s PC was showing the dreaded Blue Screen of Death on bootup; it’s a Dell, with a some built in diagnostic tools on another partition, but all the tests ran absolutely fine. Booting from a Windows CD and dropping into the recovery console, it couldn’t find the hard drive at all, so it wasn’t possible to run chkdsk or fixmbr. UBCD to the rescue! A DOS NTFS utility on it found the NTFS partition, chkdsk’ed it, fixed some errors, and all is well again (hopefully…)
The UBCD also has CD/DVD burning utilities to save data, just in case you can’t get a hard drive booting again, anti-virus/malware tools in case they were the cause of your problems, and a whole bunch o’ other stuff. Hopefully you’ll never need it, but just in case, it’s a damn handy thing to have around.