Have a look in the control panel | add/remove programs, and see if a remove tool is there for the google toolbar. An update, or new program is probably the source, the usual question to proceed is now to install this crap. here is more info.
http://www.java.com/en/download/help/5000012600.xml use google for more help. or use firefox/seamonkey to browse instead. these are not prone to this hijacking.