Winmail "find message" not finding some e-mails

Moving from Vista to Win7, I opted to continue use of Winmail. Found instructions on how to install somewhere (I don't remember if they came from here or not), but all went well and was working fine for a few months. Suddenly, searching for e-mails from certain people or addresses was not finding anything, but searches for other people or addresses worked fine. New e-mails from the same people or address are found okay (i.e., search for emails from Susie but nothing is found, but emails from Susie after the problem arose are found). I can't seem to find a solution and don't know what caused the problem. The emails (returning to the example from Suzy) are there, just can't be found from the find function like they are invisible or hidden. Any suggestions? Thanks in advance for your help and sorry if I am unable to make myself clear.

Tried these suggestions with no dice. E-mails are there but "find" won't find some of them. Any other ideas? Thanks.

Windows Mail

This might be where you found the instructions & would be the best place to ask questions concerning WM on w7.