I see you also have a problem with explorer.exe in this post;
http://forums.cnet.com/5208-6142_102-0.html?forumID=5&threadID=258487&messageID=2551849
Related?
I would scan for malware first. Viruses, spyware, and trojans.
Mark
explorer.exe drive not ready- Drive A: may be open
this message is appearing everytime my windows xp sp2 starts, since YESTERDAY,
The Drive A: is the floppy disk
i dont know what to do
how can i close it
should i open my pc and on the inside of it maybe something could be wrong there!
please help.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic