A bug has been discovered in vBulletin 3.6.1 that can result in data loss when the automatic thread redirect deletion system is used.
If you use this feature, we recommend that you download and install the patch provided here or in the members' area to prevent any possible data loss. See the end of this post for more patch information.
The members' area has been updated. If you download vBulletin 3.6.1 after the time of this announcement, you will not be affected and need not apply the patch.
Note that
only versions of vBulletin 3.6.1 downloaded prior to the posting of this announcement are affected by this problem. vBulletin 3.0.x, 3.5.x and 3.6.0 are
not affected.
vBulletin 3.6.2 will be released in the next few days and will contain a full fix for this problem along with fixes for some other less serious bugs found in vBulletin 3.6.1.
Patch Information
You may download the patch from the bottom of this post or directly from the members' area
here. Both patches are identical.
All you need to do is overwrite the functions_forumdisplay.php file in the includes/ directory of any vBulletin 3.6.1 installation. Details are also included within the patch zip file.
More... 
vBulletin 3.6.1 Data Loss Issue (With Patch) 
Linear Mode
