BSoD during idle

For the past week my pc (built 3 months ago) has rebooted when i walk away for 20 or so minutes
When i come back i find my computer at the login screen
During regular use there's no problem at all which i find quite odd

The only thing ive installed that recent is a Logitech K340 keyboard, the unifying reciever software, and the latest CCC
No idea if its a driver issue, the ram or something else =/

From event viewer:

Code:

- System 

  - Provider 

   [ Name]  Microsoft-Windows-Kernel-Power 
   [ Guid]  {331C3B3A-2005-44C2-AC5E-77220C37D6B4} 
 
   EventID 41 
 
   Version 2 
 
   Level 1 
 
   Task 63 
 
   Opcode 0 
 
   Keywords 0x8000000000000002 
 
  - TimeCreated 

   [ SystemTime]  2011-01-07T09:58:34.884823400Z 
 
   EventRecordID 42175 
 
   Correlation 
 
  - Execution 

   [ ProcessID]  4 
   [ ThreadID]  8 
 
   Channel System 
 
   Computer Kevin-PC 
 
  - Security 

   [ UserID]  S-1-5-18 
 

- EventData 

  BugcheckCode 59 
  BugcheckParameter1 0xc0000005 
  BugcheckParameter2 0xfffff88004909817 
  BugcheckParameter3 0xfffff880082c0900 
  BugcheckParameter4 0x0 
  SleepInProgress false 
  PowerButtonTimestamp 0

Dumps blame atikmdag.sys, your ATI display drivers

- Boot into safe mode with networking
- Uninstall the ATI drivers including Catalyst Control Center
- Use driver sweeper to remove leftover ATI display driver files Guru3D - Driver Sweeper
- Install the latest drivers ATI Radeon
- Reboot into normal mode

Code:

BugCheck 3B, {c0000005, fffff880048c6817, fffff880083cc900, 0}

Probably caused by : atikmdag.sys ( atikmdag+90817 )