This from 3.8.3 may give a clue:
[2013-11-26 11:54:02] SEM: Icarus USB open failed '/tmp/cgminer-usb-1-58' err (24) Too many open files
It revives the zombies until it runs out of file descriptors on unix. Maybe some similar resource exhaustion is happening on Windows?
Summary of runtime statistics:
[2013-11-26 11:54:14] Started at [2013-11-23 11:22:25]
[2013-11-26 11:54:14] Pool:
http://api.polmine.pl:8347 [2013-11-26 11:54:14] Runtime: 72 hrs : 31 mins : 49 secs
[2013-11-26 11:54:14] Average hashrate: 1298.2 Megahash/s
[2013-11-26 11:54:14] Solved blocks: 0
[2013-11-26 11:54:14] Best share difficulty: 204K
[2013-11-26 11:54:14] Share submissions: 47169
[2013-11-26 11:54:14] Accepted shares: 46323
[2013-11-26 11:54:14] Rejected shares: 846
[2013-11-26 11:54:14] Accepted difficulty shares: 76307
[2013-11-26 11:54:14] Rejected difficulty shares: 919
[2013-11-26 11:54:14] Reject ratio: 1.8%
[2013-11-26 11:54:14] Hardware errors: 837
[2013-11-26 11:54:14] Utility (accepted shares / min): 10.64/min
[2013-11-26 11:54:14] Work Utility (diff1 shares solved / min): 13.76/min
[2013-11-26 11:54:14] Stale submissions discarded due to new blocks: 0
[2013-11-26 11:54:14] Unable to get work from server occasions: 0
[2013-11-26 11:54:14] Work items generated locally: 130566
[2013-11-26 11:54:14] Submitting work remotely delay occasions: 0
[2013-11-26 11:54:14] New blocks detected on network: 508