I am running Outlook 2007 on Vista Ultimate 64bit. I only have the
necessary programs loading in startup, but I am experiencing performance
problems in Outlook emails, and sometimes calendar.

Significantly, on many occasions when I try to change email folders, like
from 'inbox' to 'sent', The screen fades to half grays and I get the message
'Outlook not responding' with the options to restart or close etc. On one
occasion a mail that I had 'sent' disappeared altogether, was not in Outbox
or drafts, and was not received by the recipient.

Help About shows: Outlook 2007 (12.0.6300.5000) SP1 MSO (12.0.6213.1000)

Does anyone know if there are performance patches or fixes that I could
access? I'm not a technician, and I would appreciate any advice on offer.

Thanks