I like this program because it allows me to detect malware or other nasties that may have invaded my comp without my knowledge. When I ran the latest scan, it showed quite a few entries that look like this:

O23 - Service: @%SystemRoot%\system32\Alg.exe,-112 (ALG) - Unknown owner - C:\Windows\System32\alg.exe (file missing)

I have quite a few of these type entries. So I scanned the net and came up with this web site that explains what the entries are:

Understanding and Interpreting HijackThis Entries - Part 1 at Malware Help.Org - Spyware Removal and Prevention Help

Might come in handy.