Outlook 2007: send receive problem when machine locked.

Hi,

I am using Outlook 2007 on a windows 7 machine. The problem that I am facing is that when my machine is locked the outlook will not do a send and receive. So, when I unlock the machine I will have to do it explicitly/manually or wait for the automatic send and receive to kick in. But this kind of takes a lot of time if the mails have queued up and I have to wait the whole while for all of them to download; this also makes outlook unresponsive if I try to open any mail during the send and receive.

I am sure there must be a small setting here or there which I am not aware of.

Request you guys to kindly guide for the same.

Thanks in advance.