If you're in this scenario, then one possible solution is using AVERT, an anti-spyware program that applies a number of spyware detection motors from different leading information security companies like Trend Micro, Panda, Clamwin, Avira and Sophos.
This program comes with different analysis modes that vary in length and depth. If you choose an exhaustive analysis, it'll take a lot longer than just a partial scan which only uses some of the included search engines.
Another interesting accessory in this program is that it lets you rid your system of useless files thanks to the technology behind CCleaner, a market leader in detecting and eliminating temporary files taking up unnecessary space.
Also, AVERT allows you to do other functions like registering security copies and adjusting network settings to insure it's actually working. All this takes place while its anti-spyware software is analyzing your system.