I have problem mounting shares with samba. I can access the directory
structure after mount, sometimes I can write files, sometimes I can read
them, very often I get "Input/Output error". If I create a new file, it
appears to have no contents.

Samba version 3.0.2a from SuSe 9.1 (with only the high UID patch
applied), system SuSE 9.1. No idea what the remote system is (except
that it's a VMS doing a pretty good job for a couple hundred of Windows
machines). Here is what I find in the kernel logs after a mount -t smbfs
with the debug=4 option:

Nowe badania wykazaly ze prawdopodobienstwo zarazenia sie plcia od rodzica
jeszcze na etapie zycia plodowego wynosi az 50%. [AJ]