mersenneforum.org - what causes missing results?

It seems that the PrimeNet server sometimes fails to receive test results. For example, when I checked my account report last October, I noticed that [url=http://mersenneforum.org/showthread.php?t=9407]one L-L test wasn't accounted for[/url]. I e-mailed George about it, and it turns out that the result for M31090393, which I finished testing in March 2006, was not received by the server. George had to manually add it to the database. This would explain why one test didn't get credited by PrimeNet. (According to the [url=http://mersenne.org/ips/manualtests.html#checkins]account update form[/url], manual submissions are not credited by PrimeNet.)

Does anyone the possible causes of this? Is there anything I could do prevent this from happening again? I would hate to lose weeks of work because some glitch happens and goes unnoticed until it's too late.

(I also have a side question: are manual results going to be credited by PrimeNet in v5?)