Have you booted in "Safe Mode" yet? If not, try that. If "Safe Mode" doesn't work, describe what you see when you try to boot in "Safe Mode".
It sounds like you might have either (a) a hardware problem, or (b) malicious software that has screwed up Windows. (It could be that USERINIT.EXE is screwed-up. That's what runs immediately after you logon, and I've heard anecdotal reports of malicious software rendering the machine into a state you describe after toying with USERINIT.EXE.)
"Safe Mode" will probably get you in. If you do get in, copy the data off to a USB memory stick, etc, and plan on leveling and re-building the machine.
"savedump.exe" is a process that runs on the next boot subsequent to a kernel "STOP" (aka "blue screen") to move the memory dump file that was generated during the STOP. "savedump.exe" isn't a malicious program or anything, though it does sound like it's having a problem performing its function (which makes me wonder if there's a hardware problem).
It's sounding more and more like just pluggin the hard disk drive into another machine (via a USB to IDE/SATA adapter, more than likely) would probably be easier than "teching through" this problem.
Here are some options:
You could attempt a "repair install", but you may get through all of that and find out that you're no better off. This might render Windows working properly again, though, too. (I'd give it 70 / 30 odds against...) This doesn't really put the data at risk, but I'd consider it my least preferred option.
You could do a "parallel install" of Windows (i.e. a second install of Windows into a directory named something other than "\WINDOWS") and use that to get at the data files. This will get you to the data and shouldn't put it at risk, but will take awhile.
You could boot one of any number of Linux-based recovery CDs (http://www.sysresccd.org is one with a fairly nice GUI) and try to copy the data off that way. If you're comfortable doing that it might be a way to go. Just be sure you select "read only" to any prompts about mounting the hard drive to keep the data safe.
Finally, you could pull the drive and attach it to another computer. That would be what I'd do, but I have a USB to IDE/SATA adapter sitting beside me. >smile<