IE6 Screen Freezes

We are facing screen freezing problems with a web based application.While working on this web based application, the screen appears to be frozen as none of the objects on screen seem to work; sometimes the buttons do seem to be active but they appear grey after clicking on them. Refreshing the page doesn’t help; and the only option is to close this browser and open a new browser in which application seems to work fine again. Sometimes there’s a blank screen which remains for about 5mins and the application dies down saying “The page cannot be displayed”. The problem is intermittent and can’t be attributed to any particular action in the application. The problem is not with only a specific PC and has been reproduced from other user's PCs as well. We have not faced this problem using Mozilla Firefox. Tried rebooting, clearing cache but it doesnt help. The browser session which is frozen can open any other site but doesnt open the application URL. DB logs, Apache logs do not show any errors. We have tried upgrading to SP3 but it didnt help.