Once you have re-enabled Polaris, then cleared data, reboot the phone (battery pull or power off/on with Fastboot disabled), then open the Polaris app by itself first, if it opens fine then try opening an email with attachment... I know Polaris works, I use it on my phone and it opens Excel files with no problems.
If the problem continues, I think a Factory Reset would be in order, especially if you haven't done one since you got the OTA update. Of course, if you could always just disable it again and install one of the above options, but if Polaris is messed up the chances something else is as well is pretty good, so I would go with the Factory Reset option, but it's your call.