Any particular pages - for example, secure "https" pages - and have you changed anything such as installing a router?
The MTU (Maximum Transmission Unit) setting can cause problems with, in particular, secure web pages. Its default setting is normally 1500 but should be reduced to 1492 with ADSL. If problems persist, try 1450 and AOL requires 1400. A router normally has an option to set the value but if connecting directly with a PC to the modem, CyberTweak click here has an option to set the MTU value.