Please forgive me, but the first thing that came into my head was 3 women all having a similar problem, so the question is, have they shared something between them that may have infected their PCs!
(yes I know, it could have been 3 guys, but it wasn't)
Obviously in one case it's now too late as the PC has been to the shop, but for the other's, then a jolly good clean-up seems to be called for, and finishing off with a good monthly system defrag.
Eusing Free Registry Cleaner (Free)
SUPERAntiSpyware Pro (Free)
Avast Antivirus (Free) (yes recently dumped AVG and gone back with Avast)
AVG PC TuneUp 2015 (don't ask)
Apart from Avast and Spyware Blaster, all the above programs are just run on a as and when basis.
Sometimes just for the hell of it I will run those programs in the reverse order because after CCleaner not a lot of rubbish is usually found, so it just makes me feel better when run in reverse the other programs pick up on the rubbish for a change.
(Please note, when saying 'rubbish' basically I mean PUPs and cookies, fortunately I don't get any/many problems with virus's.)