windows error -1 and 33

[Don Bush]

we have a point of sale system that has been in place for about a year now.
lately we have been getting a lot of  printer errors on the epson 
tm88ii receipt printers
which caused a windows error -1  requested device not 
available.  this causes the POS
system to error out and return to the menu.
We are also randomly getting a windows error 33   cant access a file 
because another process
has locked a portion of the file.
How can we stop this or trap it so we don't loose the header record 
of the sale. ANY IDEAS
We are running 5.0.14 on windows XP with a mapped drive F: from a W2k3 server.