Very slow boot

[foreright]

This morning I found that my PC takes an eternity to boot up. After 15 minutes or so the PC is ready to use but executing any function similarly takes forever.
Any ideas please as the PC is unusable but I hope is is something simple - no chance.

 

[foreright]

AMD 7750 dual core and 4 Gb Ram running XP SP3. I have had this a couple of years and it has been OK. I am attempting CC cleaner and hope to run Spybot after but they will take some time.
When I first turned it on this morning it was OK but then went really slow. On reboot the initial boot takes some time before you even get to windows. If the MB battery is low can that cause this problem?

 

[foreright]

I cannot check that right now as I'm scanning. Surely if that was the case that would only affect the boot up and not the slow execution of the programe when windows is up an running (albeit after 15 minutes)