LOCKDEBUG panic in ucom/uvisor

[Aleksej Saushev <asau%inbox.ru@localhost>]

  Hello!

For several recent days (2 or 3) I can't write anything via uvisor
(reading from uvisor is OK), the kernel panics:

#23 0xc02b4202 in panic ()
#24 0xc02adf13 in lockdebug_abort1 ()
#25 0xc027b76d in cv_broadcast ()
#26 0xc02cb9a4 in ttypull ()
#27 0xc0399176 in ucomstart ()
#28 0xc02ca2d8 in ttstart ()
#29 0xc03990d2 in ucomwritecb ()
#30 0xc0393bf3 in usb_transfer_complete ()
#31 0xc01b610e in uhci_idone ()
#32 0xc01b6345 in uhci_softintr ()
#33 0xc0299c69 in softint_dispatch ()
#34 0xc0100eed in Xsoftintr ()
#35 0x00000000 in ?? ()

The panic is 100% reproducible: I can read from Palm device
("pilot-xfer -u"), but cannot write to it ("pilot-xfer -i").
Does anyone know how to fix this?