This might be something CataLook support can best answer but I am posting it here also in case anyone has any insight into this problem .... this is totally inexpliable to me at present, and very worrying as the site goes live in a few weeks!

I am building an e-commerce site based on DNN 4.3.6 and CataLook 5.0.3. The site is in its own copy of DNN (no other portals) and its own app pool. It is on a dual 2.8GHz Win2003 server with 1GB ram and SQL Express (staging server - production server will be better spec). The address is http://62.49.66.116

Here's the problem - everything will be working correctly, and then something seems to trigger CataLook to start behaving strangely, as follows:

• clicking on a product in a product list page (e.g. http://62.49.66.116/ShopOnline/Jeans/EarnestSewn/tabid/553/List/0/CategoryID/65/Level/a/Default.aspx) just causes the page to refresh rather than leading to the product detail page (this is if you are not logged in - if you are logged in you can click through to the product detail)
• if you happen to be on a product detail page, clicking Add to Cart has no effect - cart is not updated
• on the cart page, attempting to change quantities or remove an item has no effect
• browsing the rest of the site, logging in and out all works fine - it just seems to be CataLook that stops working
• after 10 or so minutes the CataLook pages begin to start work again. I say begins to because the problem only partially resolves - some products on my sample page above click through to product detail but others still just cause a page refresh!

Two things have been found to reliably trigger this behaviour:

1. Editing the Text/HTML module in the footer of the page. I have made this editable to all users in case anyone wants to try it.
2. Completing checkout and clicking Cancel Purchase on the WorldPay page.

I have looked for clues in the DNN log, Windows application and system logs and the SQL Server log. There are no errors in any of these at the time the behaviour is occurring.

I have tried all the following to eliminate the problem and/or pin it down:

• restarting the application by opening and saving web.config. If the behaviour was happening, it continued after doing this.
• removing all 3rd party HTTP modules from web.config. The site runs with Snapsis PageBlaster, OpenDNN KeepAlive, BTB Google SiteMap and TomThorp's SSL module. This also had no effect.
• restarting the server itself. Amazingly, during an episode the problem continued to occur even after the server was rebooted !!!!

I have noticed some other wierd things with this site that may possibly be clues ...

• There is a page on the site called Resources. If this page is visited it causes the following error in the Windows system log:
  

  A process serving application pool 'AppPool #5' suffered a fatal communication error with the World Wide Web Publishing Service. The process id was '2764'. The data field contains the error number.
  
  This page only contains a few Text/HTML and Efficion Articles modules.

• I have 3 other CataLook based sites on the same IIS server. Each site is in its own copy of DNN and its own app pool. I once saw some products from this site appear in the shopping cart of another site.