This could be a problem with the hard drive itself or just corruption.
I would run chkdsk on the disk, SFC /SCANNOW and possible run a drive fitness test.
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* Bugcheck Analysis *
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Use !analyze -v to get detailed debugging information.
BugCheck 24, {1904fb, b2c0357c, b2c03160, 8348b133}
Probably caused by : ntkrpamp.exe ( nt!RtlAppendUnicodeStringToString+43 )...