You're the third person who's managed to do that and post here. See either thread:

Dosbox screwed up my computer - need help!!
Re: I dont know if this is Dosbox's fault or not but...help!!!

I've tried everything in both threads, but nothing seems to work. I can't even reach regedit, safe mode doesn't allow me any more access. Deleting it is impossible...nothing seems to work.

Would Ctrl+Alt+Del -> Task Manager -> File -> run work?

I exported the exe handler information from windows registry into the attached file (you need to rename it from .txt to .reg). Run it (doubleclick, or rightclick->merge) to add the information to the registry (it modifies .exe and exefile keys under HKEY_CLASSES_ROOT). I've got Windows XP, but it might work in Vista.

I'd really like to know how you managed that. Did you follow a guide or something that had steps written down on how to install xcom?

No, I didn't follow a guide. However, it seems (at least from the other threads I've found) that something about the combination of Power ISO and dosbox might be the problem.

I'm currently on a lab computer, but when I get home I'll try the exe file you attached, ripa. I found something like that in one of the other threads, and it said something about some keys still being open (even in safe mode it said this), but I'll try anyway.

The sad thing is, at this point, it won't even let me do a system restore. I put this computer together myself, so there is no factory settings switch, and when I try to pop the cd in and select it....more dosbox.

The Windows Vista installation cd, that is.

If the .reg file trick doesn't work (since it's not a .exe, it shouldn't launch dosbox when you use it), you should boot from the vista cd (set the optical drive as the primary boot drive in BIOS). I have XP, but XP allows me to perform a repair installation if you boot the installation disc. It fixes Windows but keeps your apps, data and settings.

Thanks ripa!! After trying everything in all of the other threads, that was the only thing that worked.

Just to repeat for anyone reading this later:
Hold del during boot up to access bios.
Change primary boot drive as cdrom (optical drive)

From there you'll have many options. I just performed a system restore, although I'm sure you could access regedit from the command prompt (which you could then use) from there (don't know why you would want to, but it's an option). Your icons will still be messed up, but creating knew shortcuts is a small price to pay for having your programs intact.

Thanks everyone!!

Just as a side note: if you want your icons back, just copy and paste them again. When they paste they should be fine. Worked for me.