Easy permanent fix
Fueldump you dont need to reinstall IE to fix this. The reason you see this message is that IE is having trouble reading the web page. This is always due to an error on the part of the person who wrote the web page. Essentially its asking you to fix someone elses mistake.
Click tools - internet options - advanced
You will see that the Disable script debugging is unchecked. Check this and then uncheck the Display notification about every script error box just below it.
You will never see the Runtime error window again..
This is from the Windows XP Timesaving Techniques for Dummies book. Cant speak highly enough of this book.