file copy problems

Hi,

I've got a pc, a laptop and a Linksys wireless router. The pc is wired and
the laptop is wireless and both running XP Pro sp2. Both access the internet
ok but I can't copy files from one pc to the other.
I've shared the folders on both as Full.
If I copy a file (MyFile) from the laptop to the pc, it starts to copy then
errors "Cannot copy MyFile: Invalid File Handle". But occasionally it does
manage to copy part of it, but its corrupt.
If I copy from pc to laptop it says "Cannot copy MyFile: Access is denied"
I've also tried disabling norton av/firewall and windows firewall on both
but makes no difference.

Any suggestions? I'm new to wireless so I must be doimg something wrong.
I've never had this problem with wired.

Thanks,

Matt.