If you have not done so lately, restart the iPad.
It's also not a bad idea to clear Safari's cookies and data now and then. You'll find that under Settings > Safari.
iOS 5 is also showing a slightly higher rate of crashes and app problems than iOS 4; especially on the iPad 1. This will probably smooth out with additional updates to iOS.
Here are the other, usual, fixes for iPad and app problems; in case you don't know about them, or haven't tried them yet.
Close/Clear the app: With the problem app closed, double tap on the Home button to get the multitask bar. Tap and hold on any icon in the bar until they jiggle, then tap the minus sign on the problem app. This will remove it from RAM and insure a clean start the next time you launch the app.
If that does not work try a restart,
Restart: Hold down the power button until the power off slider appears. Slide it off. When the iPad finishes shutting down, hold down the power button again until the Apple logo appears.
and then a reset if that does not work.
Reset: Hold down the power and home buttons until the Apple logo appears. The iPad will reboot. This usually takes a bit longer than a restart.