I suggest you might try a System Restore point to before you were installing the latest Incredimail update.
To choose a System Restore point,
· From the Desktop click the Pearl (start) button
· In the Search Field type “System Restore” and hit enter
· Once System Restore is open, select the option “choose a different restore point” and hit next
Once on the next screen, pick a restore point to go back to when it last worked for you. Once you select the restore point, click next, then select finish, this will start the restore process.