If the 'racing' is only on line, it could be a browser problem. I used to have this on certain sites with an older version of Netscape on Win 3.1. The drive would just buzz away like a fly caught in a window. A scandisk would reveal that some cache files had become crosslinked or otherwise corrupted. Try emptying your cache, and keep track of whether the problem involves particular websites, or is random.

Is the scanner a parallel or USB? If parallel, it might not like the default ECP port setting of the computer. Try going into the setup and resetting the parallel port to EPP.

My computer also froze after I installed Mustek 1200CP scanner and software. I fixed this by going to msconfig, startup and disabling any software that came with it there. Including Watch, Instant Access Control Panel and any registration reminders. This seemed to have cured it for me.