Error ??? Ammo

[FIREWALL]

Hi Captains I hope this doesn't happen to anyone else. Iwas on my way to US east coast when i stumble'd on to a lg convoy. I got myself ahead of it and followed tips from the forum on the better ways to attack. They worked great. Expended all torps, sunk 2 lg tankers, 1 med tanker, and 2 lg cargo's with stern tubes. Swung around and found a fiji on my tail at 1800 mtrs. When my last 2 internal stern T-2's were loaded that fiji was 600 mtrs and closing dead astern. I let go both eels then crash dived to 150 mtrs. Heard 2 hits. Stayed down till conoy and 2 corvettes were a good 25km away. Surfaced to peri depth looked around saw fiji breaking up and sinking. SO:SHE'S GOING DOWN!!! I surfaced and loaded external torps. everything was going fine when i had to go and click on the deck ammo icon. The screen went black and i got an error message and lost everything. This was my first patrol at 100% realism. I wanted to do this like a real U-boot Kapt. WHAT THE HELL HAPPENED???? I hope everyones patrols go better than mine did. Good Hunting