If you are using the 64 bit version and are experiencing Access Violations when typing in a grid, you can download the following fix:
http://download.allroundautomations.com/plsqldev1300x64b1d.zip
Unzip the file into the 64 bit installation directory to replace the plsqldev.exe file.
http://download.allroundautomations.com/plsqldev1300x64b1d.zip
Unzip the file into the 64 bit installation directory to replace the plsqldev.exe file.