I don't recall ever seeing this behavior before, and I've been working with VCM a long time.
What version is this?
DId it ever work? If so, when did it stop working?
Are you getting the same error when running Internet Explorer directly on the Collector as you do when running it from a remote machine?
Checking the Windows IIS logs (text logs) would be a good way to get more details of the error, as it appears to be an IIS-generated error.
It works fine from the local machine's desktop. From my machine using IE, which has been working fine for over a month, I get the above behaviour.
Checking the IIS logs shows no errors.
Do you have any antivirus software that may be preventing access to the VCM URL(s)? Have you tried clearing the IE cache on the machine where the error is occurring? You can also try using the suggestions in: FIX: Http.sys rejects requests that contain separator characters
I am also getting this error. I had it with VMWare Fusion 6, and now that I have upgraded to VMWare Fusion 7 the error still happens ( frequently ).
