PHP fatal error

[John Lester]

No, no language packs used.

EDIT: I used winmerge to compare a clean file and the live file and they are identical. So we know nothing is wrong with the file itself.

Could a style be causing this? I do have a few styles installed.

EDIT 2: This is how long and how often this error has been occuring. As you can see it's erratic and I can't find any other errors or slow queries to correspond with the dates and times.

[21-Aug-2011 07:16:32]
[22-Aug-2011 06:54:29]
[23-Aug-2011 17:33:24]
[23-Aug-2011 17:38:54]
[24-Aug-2011 04:40:42]
[24-Aug-2011 19:32:14]
[25-Aug-2011 09:16:58]
[26-Aug-2011 12:11:21]
[29-Aug-2011 04:35:31]
[29-Aug-2011 04:35:31]
[31-Aug-2011 01:56:08]
[03-Sep-2011 22:16:53]