You’ve a computer running Windows Vista Service Pack 2 or Windows Server 2008 SP2. When you install a third-party Windows Filtering Platform (WFP) callout driver. In this situation, you may receive following Stop error message on a blue screen: STOP: 0x0000000A (parameter1, parameter2, parameter3, parameter4) IRQL_NOT_LESS_OR_EQUAL. Note: four parameters in the Stop error message may vary, depending on the configuration of the computer. Not all “Stop 0x0000000A” error messages are caused by this problem. WFP callout drivers are usually used in third-party antivirus and firewall programs. “After third-party WFP callout driver intercepts a User Datagram Protocol (UDP) packet, the driver clones and then holds back cloned UDP packet. Then, driver checks cloned UDP packet and injects cloned UDP packet back. If WFP callout driver doesn’t finish checking and injecting cloned UDP packet back, the WFP callout driver will try to intercept a second UDP packet. This causes a race condition to occur,” explained Microsoft in KB976529. You can request the hotfix here.