windows 7 reboots when i try to shutdown

there seams to be an issue with my win 7 system when i ask it to power down i.e. hibernate or shutdown it reboots instead i know this is not a hardware issue as it powers down as expected under linux systems but dosnt under windows 7 can any1 help me system specs follow: 

Component Details
Processor AMD Athlon(tm) 64 X2 Dual Core Processor 6000+
Memory (RAM) 4.00 GB
Graphics ATI Radeon HD 3300 Graphics (Prerelease - WDDM 1.1)
Gaming graphics 2175 MB Total available graphics memory
Primary hard disk 29GB Free (74GB Total)
Windows 7 Ultimate

scores
processor 6.2
RAM       5.9
Graphics  3.9
gaming graphics  5.3
primary HDD   2.9
overall score (by lowest subscore) 2.9

System  
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  Manufacturer BIOSTAR Group
  Model TA790GX 128M
  Total amount of system memory 4.00 GB RAM
  System type 64-bit operating system
  Number of processor cores: 2
 
Storage  
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  Total size of hard disk(s) 74 GB
  Disk partition (C:) 29 GB Free (74 GB Total)
  Media drive (D:) CD/DVD
 
Graphics  
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  Display adapter type ATI Radeon HD 3300 Graphics (Prerelease - WDDM 1.1)
  Total available graphics memory 2175 MB
        Dedicated graphics memory 640 MB
        Dedicated system memory 0 MB
        Shared system memory 1535 MB
  Display adapter driver version 8.56.1.4
  Primary monitor resolution 1024x768
  DirectX version DirectX 10
 
Network  
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  Network Adapter Realtek RTL8168C(P)/8111C(P) Family PCI-E Gigabit Ethernet NIC (NDIS 6.2)
 
 

i could do a complete hardware profile dump here but will leave it at that for now