Turbo Mode problem

[E4T]

I have 2 the same Raspberry Pi's (model B 256mb) and both have the exact same SD card, 8GB Class 10.

Both running same Xbian Alpha 5

Using a Mysql server

I overclocked both installs to Turbo Mode.

One of them works fine, no problems at all

The other one not so!
When the Pi is running on Turbo Mode and I go to settings and programs etc, no problems. But if I go to Movies or TV Shows and it starts to load the thumbnails and or movie it automatically reboots every time! I have exact the same settings on both Pi's but one of them refuses to work! :-(

Any help please?