Import Error undefined symbol : in gnuradio while running any of the examples on usrp

hi ,
when i try connecting usrp and then run some examples i always get this
import error, I have attached the error log below. I have installed
gnuradio 3.1.3 on ubuntu 8.04 and have python 2.5 . i tried finding abt
this error but didnt get anything similar. please help.

root@warrior-laptop:/usr/local/share/gnuradio/examples/usrp# python
Traceback (most recent call last):
 File “”, line 25, in
   from gnuradio import usrp
 File “/usr/local/lib/python2.5/site-packages/gnuradio/”, line
26, in
   from gnuradio import usrp1             # usrp Rev 1 and later
 File “/usr/local/lib/python2.5/site-packages/gnuradio/”, line
6, in
   import _usrp1
ImportError: /usr/local/lib/python2.5/site-packages/gnuradio/
undefined symbol: _ZN10usrp_basic22_write_fpga_reg_maskedEiii

Ashwin R.
Comp. Engineering.