Hey I found this ...
"...However, there are some odd quirks I experienced. When you run the battery down, the X50v tends to "lose" one of the expansion cards... often the SD card will disappear from the handheld. On rare occassions, both the CF and the SD card will disappear. This often happens when you turn on the handheld with a run down battery. The problem is easy enough to correct... you have to take out the disconnected card and reinsert it. This is not a problem strictly with the X50v... I've had it often with the AudioVox Maestro and the older Axim X5 advanced. It is an annoying quirk however.."
taken from
http://www.dealtime.com/xPR-Axim_X50...D-164035595908
more ...
http://pdaphonehome.com/forums/showthread/t-49516.html
As I mentioned before, for me, it happens mostly after soft resetting.
But it happened only 3 or 4 times in 4 month so .. it's a bit rare
Lior