Local_scan timeout -- config issue?

I am running Exim 4.63 with sa-exim on a Sunfire V210, Solaris 10. Nothing
has been altered for a couple of months.

Over the past couple of days, I have been seeing the following messages in
my logs from time to time:

2006-12-19 11:03:00 1GwckM-0005Wz-UQ SA: Debug: SAEximRunCond expand returned: '
1'
2006-12-19 11:03:00 1GwckM-0005Wz-UQ SA: Debug: check succeeded, running spamc
Dec 19 11:03:00 spamc[21268]: [ID 702911 mail.error] skipped message,
greater than max message size (272384 bytes)
Dec 19 11:08:00 spamc[21268]: [ID 702911 mail.error] oops! message_dump of
8192 returned different
Dec 19 11:08:00 spamc[21268]: [ID 702911 mail.error] oops! message_dump of
4288 returned different
2006-12-19 11:08:00 1GwckM-0005Wz-UQ local_scan() function timed out - message t
emporarily rejected (size 320896)

I have SAmaxbody left at the default and SATruncBodyCond: 0.

Have I messed up the config somewhere? I was under the impression that I should
get a message along the lines of:

2006-12-19 02:13:47 1GwUSy-0004kn-UH SA: Action: check skipped due to message si
ze (8885632 bytes) and SATruncBodyCond expanded to false (Message-Id: 1GwUSy-000
4kn-UH).

Thanks,

Jon

Systems administrator
365 Media Group