I discovered that one of the memory sticks in the machine was damaged. Running memtest86 on the machine generated many RAM errors. This was causing the strange bi-polar errors in postgresql.
The hardware technician explained that he sees this often and that there is no one cause for such problems. As I am not a hardware specialist, I never thought that RAM could cause such problems. I always assumed that the OS (ubuntu or windows) would advise me if there was ever an issue with memory. TAKE AWAY: As a result of this I will be checking the RAM on all my machines once a month or the moment a machine starts to act strange. Thanks again to all who helped with this issue.
