HKLM\SYSTEM\CurrentControlSet\Control\Session Manager

Data type


Default value


0x0–0xFFFFFFFF ( four-second units )

648000 (648,000 four-second units = 30 days)


Determines how long the system waits for a locked kernel-mode resource to become available. When a resource is unavailable, the system waits for 500 milliseconds. If the resource is still unavailable, the system increases the priority of the thread using the resource, in order to speed its completion. It then waits for up to the number of four-second units specified by the value of this entry before terminating the request. If the resource becomes available before this time expires, the timing stops, the timer reinitializes, and the resource is released to the waiting thread.

A resource that remains unavailable for more than 30 days typically indicates a problem that should be investigated and resolved before proceeding.