We have a web site running in windows server 2008r2 iis7.5 and we are seeing several errors reported from our global error handler saying that "Request Timed Out". I matched up one to the IIS log file and see the request took 135116 (presumably milliseconds) had an sc-status of 401 an sc-sub0status of 0 and an sc-win32-status of 64.
2 requests failed in these way but lots of surrounding requests (1979 successful requests vs 2 fails) for the same user went through perfectly fine- with the same cs-username which makes a 401 seem a little odd.
The target of the requests is an ASP.Net web service's web method called by the .net client library- it's called a lot of times per user (3 times per second) to keep a page updated.
We're getting some users reportng seeing a freezing effect and I think this may be the cause, any ideas?