Internet connection problems

I am using a desk top pc with windows 7 and using firefox as my browser. I use a dongle fixed into my usb port. I keep having not responding problems, page cannot be displayed and page has expired etc. I have tried cleaning up virus but to no avail n have tried fixing with free method by going to tools and still it didn't work. I have disconnected my dongle from my usb port and restart my computer but it also didn't work. Pls advise and help.

You don't say what sort of dongle it is, whether it connects you to a router in your house or the mobile telephone network. But the symptoms you describe indicate a slow and/or erratic connection to the internet. It could be that the signal at your computer is too weak or your dongle is faulty. If your dongle connects you to a router then the speed of the internet connection to that router could be very poor.