Just in case anyone else runs into this today, I went to patch a system today to find this error on the Patching screen:

Patch Tips

• # 3. Patching is currently disabled for windows, because patch signatures are missing from the K1000. Please check the server logs for download errors, and rerun the patch download.

Tried the patch download several more times, found errors in the K1000 log, then did a search here in ITNinja and found this post:

Patch Tip #3 Missing Signatures
http://www.itninja.com/question/patch-tip-3-missing-signatures

My mismatched MD5s were the same each time:

[Thu Jun 14 14:55:05 EDT 2012] [notice] Patch download error, mismatched MD5 (4f9c2c9d56381a7a26010d81d0ebfca2 != b5873d3654cc8abefaa999523dc3898a)
[Thu Jun 14 14:55:06 EDT 2012] [notice] PLPatch fetching http://download.windowsupdate.com/microsoftupdate/v6/wsusscan/wsusscn2.cab

[Thu Jun 14 14:56:23 EDT 2012] [notice] Patch download error, mismatched MD5 (4f9c2c9d56381a7a26010d81d0ebfca2 != b5873d3654cc8abefaa999523dc3898a)
[Thu Jun 14 14:56:58 EDT 2012] [notice] KPatchSystem - Complete.

...so I called KACE support and after getting the issues escalated to engineering was advised that this is an issue with the file the K1000 is trying to download and should resolved some time tomorrow.  Should straighten itself out once the file issue has been addressed.

Hope that helps save someone else some time!

John