Drive Not Ready

http://i.imgur.com/fssiD.png

I get a 'Windows - Drive Not Ready' error box every time I try to open the System Startup list. The content of the error message is 'Exception Processing Message c00000a3 Parameters 75b6bf7c 4 75b6bf7c 75b6bf7c'.

I've tried disabling Symantec and running from Safe Mode. I get the same error no matter what drivers or programs are running in the background.

I've also tried uninstalling and reinstalling Spybot to no avail. This is on Windows XP SP3.