error 1203 randomly when mapping drives

Here's one that I couldn't find anywhere on the net after days of researching. I had an issue where a customer reported not being able to map a network drive from citrix servers at random times. The end users would log off and on over and over until they get the drive letter that was missing. It always happened to the same drive letter and it only happened about 25% of the time. Further research revealed a error during the logon script of [error code 1203]. The Microsoft explanation of that error is:
"System error code 1203 means "The network path was either typed incorrectly does not exist or the network provider is not currently available. Please try retyping the path or contact your network administrator." This error code may also display as "ERROR_NO_NET_OR_BAD_PATH" or as the value 0x4B3."
Since this was only happening on 1 drive letter and only from terminal servers (the citrix server piece of info turned out to be someone inaccurate.. it was actually any windows 2003 server, but only seen on terminal servers because that's the only servers that a user logon script is run on). I finally found some articles talking about DFS and the webclient service. The drive letter in question was being mapped to a server that had DFS installed, but wasn't even being used. Still...
turning on that webclient service cleared up the random 1203 errors. The webclient service is disabled by default on windows 2003, but on be default on windows 2000 and xp. It would seem it was deemed unnecessary on servers since it's a client mapping "helper" application and generally users don't log onto a servers desktop to do work. Except for terminal servers that is... almost seems like MS should turn that service on when terminal server gets setup. I plan to put in a gpo tied to the OU of the terminal servers, but for now just starting the service manually has fixed the issue.
Hope this helps someone save some time.