See if there are any other programs running that shouldn't be such as spyware or adware by pressing CTRL+ALT+DEL once to open the task manager. End task on any that are running except Explorer (which is windows), Systray, and whatever program you're using where the right click won't work.
For more information on spyware or adware, either search those words via a search engine or see www.pestpatrol.com or www.lavasoft.com.
If no adware or spyware is detected and running and the right click still doesn't work, re-install (repair) your browser--MS Internet Explorer? What version? IE 6, SP1 is the latest version I think, but I would hesitate to install the service pack as bugs have been reportedly high in that version. Go ahead and download and install any windows critical updates that repair security holes.
Please post comments with more information!
HTH