I get an intermittent Wireless tools not found error

bt ~ # iwconfig
iwconfig: error while loading shared libraries: libiw.so.28: cannot open shared object file: No such file or directory
bt ~ # airmon-ng
Wireless tools not found
bt ~ #

Seemed to originally happen if I boot up with a PCMCIA wireless adapter plugged in (Netgear WAG511) or with a USB one (Alfa AWUS036H).

After a few reboots without Wireless adapter(s) plugged in it now seems to be a permanent error
Have installed the wireless tools manually
works until a reboot then same error
have to install it manually every time I want it.

Virgin BT3 install on IDE HDD on a Vaio GRT 815E dual booting with XP.

Also get the same problem on a Dell Optiplex gx520 with same adapters - SDA HDD, default install, single boot.

Not motivated enough to troubleshoot it just yet as it is only a nuisance at the moment but will get around to it tomorrow when it starts to irk me - plus I now need to roll the laptop back to BT2 for work tomorrow :-S

Any log files/configs you want me to post, let me know.