Error 25 typically indicates that you have a bad patch file. It may have become corrupted at some point. Please try doing the following to see if it fixes the issue:

1. Rename your Inst folder that's located in your wkstn folder (in your case P:\pronet20\wkstn\Inst) to something like Inst_backup
2. On the admin machine, re-run the installer that you used to install the admin machine (Note: You do not need to uninstall ProSeries to do this)
3. Once that completes, you should see a new Inst folder created in your wkstn folder
4. Try running the workstation installer (P:\pronet20\wkstn\setup.exe) on your workstation machine

If you're comfortable trying those steps, please give that a shot and let me know how it goes. If you still have trouble, please send me an email at ProSeries_Engineering@intuit.com and put "attn Nobles" in the subject line.