Some programs losing printers

[Linda]

I have an annoying problem with 12.04 LTS.  Frequently when 
I go to print with Inkscape,  Google Chorme and Libre Office 
after they have been open for a while they have lost all of 
the printer options. If you close and reopen you can then 
print without a problem.  Just wondering if anyone else has 
encountered this problem or has any ideas on how to solve 
it? The first few time it happened I thought the CUPS server 
had died for some reason but that was not the cause.
            Thanks
            Linda