Random BSOD every 6-7 hour

Welcome

You need to update your NVIDIA cards drivers.

Code:

2: kd> lmvm nvlddmkm
start             end                 module name
fffff880`0f04a000 fffff880`0fdc4000   nvlddmkm T (no symbols)           
    Loaded symbol image file: nvlddmkm.sys
    Image path: \SystemRoot\system32\DRIVERS\nvlddmkm.sys
    Image name: nvlddmkm.sys
    Timestamp:        Sun Dec 18 01:05:56 2011 (4EECE814)
    CheckSum:         00D612A0
    ImageSize:        00D7A000
    Translations:     0000.04b0 0000.04e4 0409.04b0 0409.04e4

Option 2
Direct Download (from unofficial website):
→ Download NVIDIA Forceware 306.23 WHQL Vista 64 - FileHippo.com for 64 Bit windows
→ Download NVIDIA Forceware 306.23 WHQL Vista - FileHippo.com for 32 Bit windows

64 Bit in your case

Use the common way for uninstalling via Control Panel -> Programs -> Uninstall a program.

Suggest you to uninstall ESET and use MSE instead.
→ Microsoft Security Essentials - Free Antivirus for Windows

Run the system file checker that scans the integrity of all protected Windows 7 system files and replaces incorrect corrupted, changed/modified, or damaged versions with the correct versions if possible
→ SFC /SCANNOW Command - System File Checker

Run Disk Check on your hard disk for file system errors and bad sectors on it
→ Disk Check

Let us know the results

Did updating drivers help?

Good to hear that. Observe for a few more days if the BSODs reoccur. If not, mark the thread as solved.

Let us know if there are any other issues.