Can log in to Windows but can't open anything once I'm in and when that error message window opens, Windows crashes and the system restarts itself.

mouse.dll is not a Windows XP file. Did you load any mouse software?


Is this a new problem? Were things working OK previously? Any new hardware and or software?


Try booting into Safe Mode by repeatedly tapping the F8 key after your BIOS POST but before Windows starts.


If this is a new problem try a System Restore to a point prior to the problem:

start > All Programs > Accessories > System Tools > System Restore


If that doesn't help then:

Go to start > search > All files and folders

Set the advanced options to show system and hidden files and then type: mouse.dll

What program is the file associated with? What is its' location?