Slow logon when attempting to remap persistent drive mapping to new DFS location

When changing the mapping of an existing persistent drive map to a DFS target, we are experiencing long delays (~10 minutes) after logging in.  This is happening on all subsequent logons, so it's not a one time thing.  Users are seeing a black screen (with mouse pointer) while Windows seems to be sitting there searching.  After the wait, the drive mapping and everything else look normal.  The drive letter is currently mapped to a regular Windows share, via GPO, and this issue happens whenever we attempt to change that GPO-based mapping to the new DFS location.  Manually mapping to the new location works perfectly, but for some reason, changing the mapping wherever there is already a persistent map (either manually set or by GPO), changing the mapping seems to cause this issue.  All affected clients are using Windows 7.  Anyone else ever experience this?
Matt MarkleyServer/Storage AdministratorAsked:
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Have you done a gpresult?  Also do you have any logs you can share from the system log that would indicate anything wrong with Group Policy Processing?

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Matt MarkleyServer/Storage AdministratorAuthor Commented:
Jeff -- thanks for the response.  I've pored over both, and really didn't find anything resembling a smoking gun -- but I will clean out my logs and give it another go, just in case I missed anything.  As for the gpresult -- it's s ton of information, and I'd be the first to admit to possibly missing something.  We have entirely too many GPOs in our environment... :(

Food for thought... I could get this to replicate by simply manually creating the persistent map.  Conversely, the issue did not replicate when either not mapping the drive letter or simply creating a session mapping.  I find it interesting that the process seems to be snagging on the pre-existence of the persistent drive map.  This is clearly a key.  Now if only I could find the lock...
Matt MarkleyServer/Storage AdministratorAuthor Commented:
Problem solved!

The root cause turned out to be not one but TWO existing GPOs that were contending for the same drive letter mapping as the new one.  One was a direct mapping (via GPO) and the other kicked off a login script.  This explains both the delays and the somewhat random results I was seeing.  Once I tracked those down, it became clear that I was contending with sort of a race condition between the three mapping processes.  After disabling the other two, the new GPO worked perfectly and without delay.

Thanks again to Jeff for reminding me to slow the heck down and check those GPOs.  Our environment is a rather venerable one and is very hard to read.  Which is exactly why I miss the good old days of login scripts...  Gotta keep those GPOs groomed and documented!  :)
Matt MarkleyServer/Storage AdministratorAuthor Commented:
While the solution ultimately required further action, this suggestion was valid and led me back in the right direction.  Thank you Jeff!
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Windows 7

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