Gmail IMAP filter problems

Ok I've just about got my email under control on my Storm using gmail IMAP.

I solved the problem of sent mail returning to my inbox with a filter in BIS and in Gmail that deletes mail from my own email address.

This seems to have caused another problem though.
When I send an email in gmail online, I get a message saying I am sending mail from a 'trashed conversation' because my filter is obviously automatically deleting my sent items as well!
This also means that all the different clients are not talking to each other when it comes to sent emails. I use windows mail, apple mail, gmail online and since recently my BB.

I get the feeling there is a more advanced filter/multiple filters that I can use to stop this happening, I just don't have the brain power to figure it out!

I look forward to hearing any ideas, and please speak to me like you would a 5 year old!