bad pool caller.
this is error, doesnt always mean what it says......bad pool caller can be a broken hard drive, faulty cpu or board,and usually the memory.and i some cases a faulty pic device
firstly i would remove a stick of ram(only if you have more then one), then try again,if the same swap ram and try again..the idea being to find a faulty stick if you have one.
if not remove all pci cards and then retry....
if not the only other way is to obtain another hard drive,then re-install xp to the new hard drive....then slave your old drive,copy all your data back over to the new install....then you could format your drive and do a full install.
there are loads more avenue with "bad pool caller" but in my opinion this is what i would try.
let me know how you get on.
regards
danzil.
ps do you get any error codes if so what are they