Can't go to sleep on lid closing since update

I've updated to Mountain Lion and since then my mac keeps running like mad whenever I close the lid. It's a mid 2009 MBP.

This is what terminal gives me:


Assertion status system-wide:
PreventUserIdleDisplaySleep 0
PreventSystemSleep 0
PreventUserIdleSystemSleep 1
ExternalMedia 0
UserIsActive 0
ApplePushServiceTask 0
BackgroundTask 0

Listed by owning process:
pid 165(coreaudiod): [0x0000000100000252] 00:00:06 NoIdleSleepAssertion named: "com.apple.audio.'AppleHDAEngineOutput:8,0,1,1:0'.noidlesleep"

Kernel Assertions: 0x0128
* Kernel Assertion ID = 500
Created At = 01/01/1970 01:04:12 CET
Modified At = 01/01/1970 01:00:00 CET
Owner ID = 0xffffff8015c76000
Level = 0
Assertions Set = None (4)

* Kernel Assertion ID = 501
Created At = 01/01/1970 01:04:17 CET
Modified At = 01/01/1970 01:00:00 CET
Owner ID = 0xffffff8015c79000
Level = 0
Assertions Set = None (4)

* Kernel Assertion ID = 502
Created At = 01/01/1970 01:05:15 CET
Modified At = 01/01/1970 01:00:00 CET
Owner ID = 0xffffff8015cbc000
Level = 0
Assertions Set = None (4)

* Kernel Assertion ID = 503
Created At = 01/01/1970 01:05:26 CET
Modified At = 01/01/1970 01:00:00 CET
Owner ID = 0xffffff8015cc0000
Level = 0
Assertions Set = None (4)

* Kernel Assertion ID = 509
Created At = 20/08/2012 21:17:33 CEST
Modified At = 01/01/1970 01:00:00 CET
Owner ID = 0xffffff8015db8500
Level = 255
Assertions Set = None (128)