We own and manage our own server

. IMHO all settings are okay. Doubling memory limit to 16M doesn't help. Increasing the execution time till 900 doesn't help either.
Server settings:- Server Type Linux
- Web Server Apache v2.0.54
- PHP 5.0.5-1.dotdeb.1
- PHP Max Post Size 8.00 MB
- PHP Maximum Upload Size 50.00 MB
- PHP Memory Limit 8.00 MB
- MySQL Version 4.1.15-Debian_0.dotdeb.1-log
- MySQL Packet Size 16.00 MB
- Maximum execution time = 30
- Maximum input time = 60
GD settings:- GD Support enabled
- GD Version bundled (2.0.28 compatible)
- FreeType Support enabled
- FreeType Linkage with freetype
- FreeType Version 2.1.7
- GIF Read Support enabled
- GIF Create Support enabled
- JPG Support enabled
- PNG Support enabled
- WBMP Support enabled
- XPM Support enabled
- XBM Support enabled