We've been experiencing Slow Login and Slow Refreshes randomly throughout the enterprise. After 2 days of support and logs we found that Trend Micro 10.5 Office Scan has a bug that the exclusion list will only honor the first 1023 characters in the list. So when booting up any and all services after the C:\D*.* in the list were being scanned.

We migrated from 10.3.1 directly to 11.0 on the Primary Servers.
2 Primary Windows (Physical)
1 Primary SLES 11.1 (Physical)
1 Primary SLES 11.1 (Virtual Appliance)
Satellites and Devices remain at 10.3.1 during this issue.

Once we did the last server upgrade we started experiencing Slow logins (5-45 minutes) and slow ZCM 10.3.1 agent refresh times (800 seconds to 2 hours).

Put on the registry key from the Novell Documents ZENworks 10 Configuration Manual section "31.1.3 Displaying the Login Status Messages on the Device Screen" to display why the Blue Screen of Life was just sitting there. After applying the registry key it displayed "Novell ZENworks: Logging into User Source" and would sit there.

Now we could see what step was having an issue. Novell TID 7003932 brought up TrendMicro.

After stripping off vendor agents researching the issue we removed TrendMicro Office Scan 10.5 Client.
Logins increased tremendously, researching TrendMicro the exclusions from Version 10.0 to 10.5 were migrated but there is a bug that needs to be fixed with 10.5 patch 1 build 1766 - this doc indicates the truncation of the exclusion list and to use fix 199636/199905/200419/200586 EN_Hotfix_1106.1 in the document
http://www.trendmicro.com/ftp/documentation/readme/OfficeScan10.5Patch1_Readme.txt

Trend 10.5 Office Scan wasn't excluding the ZENworks directories specified in the exclusion list. Applying this patch fixed the issue and ZEN services, logins and refreshes came back to near normal.