paulettegrc, gandecab is bringing up some great points (thanks for the help!!), do you see any sort of data signal on your phone such as 2G, 3G or 4G? In order to access the internet one of those needs to be on your phone and I am sorry to hear you web isn't connecting consistently.
oh, you are not on a phone call, just using the web and the browser crashes?
have you rebooted the phone? you can try a different browser from the market. do other apps lose internet connection - like pandora or iheartradio or youtube? as a last resort you can do a factory reset.
What's funny is that while I was reading this thread on my Sensation, my stock browser force closed. It's been suggested that there is an app conflict on my phone, but I haven't had time to do a reset yet.
It does it on 2g 3g 4g and WiFi like I said above...and what app I never said anything about using a app is the stock web no app no other browser..and I cant exchange it Im on prepaid and didn't buy it at a tmo store