Google Toolbar Disappeared

Hi guys again I'm here having some experience to share with you also wanting to have your opinions and maybe answers to my problems. yesterday I just noticed my computer is having a hard time to connect to the internet it has limited or no connections and I've waited for hours to be stabilized but then after having a connection I immediately browse the net but my computer is too slow and always saying dns server occured or reset for couple of hours I'm so bothered because as I can see my internet modem works fine with all the lights on I felt that the problem is my computer, I'm using Firefox 3.6 and immediately view the error console,  there I found multiple errors until I finally realized that my Google toolbar is missing with no trace at all...hmmm???kinda weird right? and I think that's the problem because I use google toolbar and google search as my default browser, I traced where did it go but I failed, no trace at all I didn't uninstalled it nor hide the toolbar  it disappear instantly and I'm wondering up to now I just downloaded another google toolbar to make my computer works again and it's working now that's why I don't want to missed the chance to post about this incident maybe you could help me answer or someone out there experienced this also?I googled it and found some relevant answered in the forums, some says I should installed adware software but I scan my computer using avg and it's clean...oh boy! who do you think is the culprit ha?any idea? mystery unsolved...