Technical response: IMMEDIATELY! Cost-effective respone? IMMEDIATELY! But why? Spyware, Adware, Malware, and Viruses move throughout the internet like the plague: a couple systems get infected, and they become hosts, and then a few more become infected from those couple and it exponentially goes from there. Once your system has spyware in it, the programs these days contact outside sources to download more spyware programs into your system so your system progressively gets worse and worse each day and with each reboot.

The longer you wait to get it fixed, the more the spyware downloads into your system and the longer it takes to repair. If you wait more than a month, it's pretty much guaranteed that will have to get the system rebuilt.
You should get your PC checked and fixed in less than one week of the suspicious activity in order to drastically reduce your cost of repair.

• Forum IT