Benchmark doesn't work


I have problems with my USRP1 device. All things are installed properly
(so i hope), but i cant run benchmark or something else.

There are 2 possibilities - sometimes i got “uUuUuUuU” (overrun) as
result and sometimes it remains by “Testing 2MB/sec…” and I have no
idea what to do.

lsusrp shows
USRP 0 serial number 4e261393
RX d’board A: Flex 1800 Rx MIMO B
RX d’board B: Flex 1800 Rx MIMO B
TX d’board A: Flex 1800 Tx MIMO B
TX d’board B: Flex 1800 Tx MIMO B
so my system (ubuntu) recognizes usrp properly

also in log appears it as ehci_hcd
usb 2-1.2: new high speed USB device number 12 using ehci_hcd

and I can see it in lsusb
Bus 002 Device 012: ID fffe:0002
or in /dev/bus/usb… as usrp
crw-rw---- 1 root usrp 189, 139 2011-10-29 16:29 /dev/bus/usb/002/012

I changed already in limits.conf priority and added realtime support
gr.enable_realtime_scheduling() (it works only with root permissions)

but the result is always the same and I dont know what else to do

hope someone has some ideas
thanks in advice