This may be a big red herring.... however I could be onto something.
I was looking at poker DIY cached in google just now and got blank pages with an error. ONLY with IE8 and not all the time.
I just got:
Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; MS-RTC LM 8; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Timestamp: Tue, 21 Jul 2009 01:16:36 UTC
Message: Permission denied
Line: 3517
Char: 4
Code: 0
URI: http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js
If I click on "Text Only Version" - I get full content!
Suggestions for my crack pot theory:
* Stop jquery being picked up via http://ajax.googleapis.com and go local.
I know you can easily change the settings with DNN 5, you might need to hack DNN 4.9.4 (not sure how).
Maybe jquery is going local though, maybe google is replacing jquery code with it's own code/file path in cache for performance purposes.
* Check the text only version of google cache when you get blank content.
* Try IE8.
*Blame google maybe (like that's going to help!)