Cannot receive mail before delete mail

[Jasper]

Hi, I'm using Outlook 2000 for send & receive POP3 and SMTP mail.
Some times I cannot receive mail and the error is POP3 server error (But I
confirm the server is fine). But when I delete mail from my Inbox and
receive again, it is successfull. (Sending message is no any problem)

My question is how to fix the problem.
Have any concern for too many Inbox message. Have any guide for maximum
Inbox size for outlook 2000? (I know the PST max size is 2GB)

Thanks