Well there is no solution available (currently), I think it's maybe the cracked version? Or iFile it's self.
But I have a method to 'avoid' it from happening. So when it freezes it's some error from the last running session inside iFile App. So when you tap the icon and your device freezes the process from ifile is still continuing from the background, it's some wierd error.
Anyway my solution doesn't fix it but you will know if it will occur before you tap iFile, so you can just respring to avoid it from happening.
1. Launch Cydia -> Install 'RippleBoard' from BigBoss
2. Turn on the feature 'Running Apps' (this feature provides a bright ring constantly appearing above any app that's running in the background).
3. Now if iFile is not running in the background visually towards you, and has the ring appearing on the app that means if you tap it your device will freeze, so with this method you will know pre-handed if it will happen.
4. Respring, your good.
Hope this helped
Found by me