Read this:
Most of the people suddenly experience, that it suddenly is impossible to use the "View source" functionality in the Internet Explorer. The problem occurs due to a bug in IE if you've set your Temporate Internet Files too high. If you decrease this seting to less than 80MB, the problem stops. If not, try to delete all temporary files.
IMPORTANT Update: This sounds strange, but if you have a shortcut to Notepad on your desktop, it will also prevent you from viewing source!!!
I checked the Microsoft site for a fix, but as of yet there is none!
Solution:
Delete the Temporary Internet Files, otherwise known as the disk cache. The cache includes local copies of web pages and files, so the browser doesn't have to download them again.
In the Tools menu, open Internet Options.... In the General tab, in the Temporary Internet files section, click on Delete Files.
It seems "view source" is affected when the cache gets too large in size. Internet Explorer takes the source from the Temporary Internet Files folder to the folder specified by the TMP environment variable. Refer to Microsoft article for more information about this.


