iOS Reboot when open .exe file in iDownloader
When you say that it automatically rebooted, are you referring to an actual reboot or simply the app crashing back to the home screen?

The latter shouldn't cause any problem to your device, however if data was being written in the app, that data could be corrupt. If the device performed a full reboot, and data was being written by the OS, that data could become corrupt, however it is extremely unlikely that this will cause any problems.

iOS, like OS X, can stand being terminated mostly, with circumstances to prevent corrupt files from breaking things. If something has been 'broken' by the termination of the OS, simply restore the device using iTunes. If something has been 'broken by the termination of the app, delete and re-download the app, removing any data from iCloud Documents &amp; Data if necessary.