Virus or something else?

hotpantsgalore has a 4-year-old Acer laptop that has recently developed some super-annoying features. In particular, it can't seem to run a word processor to save its life: he cursor jumps around between lines (in fact, it does that on webpages too - dammit, that's annoying), it seems really slow, & generally it just seems to be running poorly.

She says she's run some anti-virus software checks on it, & it hasn't helped (I think she ran Kapersky?). What else should she do? Can we take it somewhere & get everything wiped off of it? I know she just wants to buy a new computer, but we really don't have the money right now.