Mac crashing suddenly and restart

Mac crashing suddenly and restart

My Mac keeps on crashing around 5 times a day which is very annoying. It just turns off all of a sudden and than start again... Crash log is provided below. Any idea as to what may cause this?
    Interval Since Last Panic Report:  932654 sec
Panics Since Last Report:          8
Anonymous UUID:                    56779F7C-88A6-E421-B2DD-F955F3A25E9A

Sat Jun  8 13:54:45 2013
panic(cpu 0 caller 0xffffff7fa06537f2): NVRM[0/1:0:0]: Read Error 0x00000100: CFG 0xffffffff 0xffffffff 0xffffffff, BAR0 0xd2000000 0xffffff809ca1e000 0x0a5480a2, D0, P2/4
Backtrace (CPU 0), Frame : Return Address
0xffffff809606b7a0 : 0xffffff801fe1d626
0xffffff809606b810 : 0xffffff7fa06537f2
0xffffff809606b8d0 : 0xffffff7fa07503b9
0xffffff809606b930 : 0xffffff7fa075042e
0xffffff809606b9a0 : 0xffffff7fa0a76c82
0xffffff809606bad0 : 0xffffff7fa0776fe8
0xffffff809606bb10 : 0xffffff7fa065b567
0xffffff809606bbc0 : 0xffffff7fa065905a
0xffffff809606bdc0 : 0xffffff7fa065a0c5
0xffffff809606bea0 : 0xffffff7fa05f8aba
0xffffff809606bef0 : 0xffffff7fa20c80df
0xffffff809606bf40 : 0xffffff7fa20c71e7
0xffffff809606bf60 : 0xffffff801fe3dcfe
0xffffff809606bfb0 : 0xffffff801feb2977
      Kernel Extensions in backtrace:
         com.apple.NVDAResman(8.1)[A26D2A3D-C06F-3A0F-BCFF-901A98C93C3D]@0xffffff7fa05f6000->0xffffff7fa0903fff
            dependency: com.apple.iokit.IOPCIFamily(2.7.3)[1D668879-BEF8-3C58-ABFE-FAC6B3E9A292]@0xffffff7fa045a000
            dependency: com.apple.iokit.IONDRVSupport(2.3.7)[38C214C0-83C8-3594-8A4C-DC6AC3FEC163]@0xffffff7fa05e2000
            dependency: com.apple.iokit.IOGraphicsFamily(2.3.7)[74E3E50F-E50A-3073-8C96-06F854292A91]@0xffffff7fa059f000
         com.apple.nvidia.nv50hal(8.1)[5F021999-8B18-3BD5-9B98-90617E638A63]@0xffffff7fa0911000->0xffffff7fa0c32fff
            dependency: com.apple.NVDAResman(8.1.0)[A26D2A3D-C06F-3A0F-BCFF-901A98C93C3D]@0xffffff7fa05f6000
            dependency: com.apple.iokit.IOPCIFamily(2.7.3)[1D668879-BEF8-3C58-ABFE-FAC6B3E9A292]@0xffffff7fa045a000
         com.apple.driver.AGPM(100.12.87)[A7004F02-7D39-3398-8BD3-729DCC404E5F]@0xffffff7fa20c6000->0xffffff7fa20d5fff
            dependency: com.apple.iokit.IOPCIFamily(2.7.3)[1D668879-BEF8-3C58-ABFE-FAC6B3E9A292]@0xffffff7fa045a000
            dependency: com.apple.driver.IOPlatformPluginFamily(5.3.0d51)[2C131EAF-F74C-39D1-A702-A499B39C293C]@0xffffff7fa1032000
            dependency: com.apple.iokit.IONDRVSupport(2.3.7)[38C214C0-83C8-3594-8A4C-DC6AC3FEC163]@0xffffff7fa05e2000
            dependency: com.apple.iokit.IOGraphicsFamily(2.3.7)[74E3E50F-E50A-3073-8C96-06F854292A91]@0xffffff7fa059f000

BSD process name corresponding to current thread: kernel_task

Mac OS version:
12D78

Kernel version:
Darwin Kernel Version 12.3.0: Sun Jan  6 22:37:10 PST 2013; root:xnu-2050.22.13~1/RELEASE_X86_64
Kernel UUID: 3EB7D8A7-C2D3-32EC-80F4-AB37D61492C6
Kernel slide:     0x000000001fc00000
Kernel text base: 0xffffff801fe00000
System model name: MacBookPro6,2 (Mac-F22586C8)

System uptime in nanoseconds: 1689732180630
last loaded kext at 239002001884: com.apple.filesystems.smbfs   1.8 (addr 0xffffff7fa2205000, size 229376)
last unloaded kext at 142236835942: com.apple.driver.AppleUSBUHCI   5.2.5 (addr 0xffffff7fa0e60000, size 6