Which gadget does this problem concern?

Gmail Icon for Google sidebar

What steps will reproduce the problem?
1. Incoming mail disappears
2.
3.
...

What is the expected output? What do you see instead?

I get the expected output, i.e. I get notified that I have new mail in my 
Gmail account. The problem is the I cannot find the mail in the Gmail 
account anymore.

What version of the product are you using? On what operating system?

2007 gadget on WinXP SP2

Which version of Google Desktop are you running and which language 
version of Google Desktop is installed? (You can find the version by 
clicking the downward arrow on top of your sidebar and clicking About...)

Google Desktop 5.5.0709.30344-en-pb

Please provide any additional information below. If you see visual issues 
please attach a screenshot to this issue.
I have two Gmail accounts, and this problem happens in both i.e. the 
gadget icon changes color, has a number in the small circle, and also 
opens a box to the left when I click the number, but I cannot find the 
message in the appropriate Gmail account, anywhere.

Thanks, mb