In general this kind of error is due to an OS or Hardware trouble (or bug).
I got this kind of error 2 times. Once it was due to a Hardware bug on the CPU - it was
solved by replacing it and, the second times, it was due to a Bug on the C-Compiler of the OS.
You should open an issue to Oracle support (Metalink) as soon as possible and give them all the
information you can (alert.log, trace files,... the accurate OS and Database release and explain
how this error happens - which statement or action generates it).
By that way they could help you efficiently.