did you try to change the mouse settings on the AVR config page.
Try to change these settings from absolute to relative (or vice versa).
Also resolution change may be helpful.
But first of all, please check your RAID FW version. There are some WebBIOS problems with older versions.
Ensure that you are using RAID FW 516G,
which is available from Fujitsu Siemens download site.
Nevertheless even with a moving mouse, working in WebBIOS via
AVR is no fun.