HijackThis: How to Get HJT and How to Analyze the Logs
HijackThis is a free tool that produces a snapshot of active items loading on the computer. HijackThis covers the most common auto start entry points so it can be useful in helping to identify malware and targeting it for removal. Hijack this is available as a free download from Trend Micro.
Analyzing the Log File::
HijackThis provides a list of both good and bad items loading on the compuer, so analyzing the results requires an experienced eye.
Though not affiliated with the makers of HijackThis in anyway, HijackThis.de Security provides free online HijackThis log file analysis. You can either copy/paste the log results into the appropriate window on the hijackthis.de website or use their browse feature to upload the entire log as a file.