Pastel Accounting

I have computer that has been running on Windows 98 and had Pastel Accounting v.5 installed.I upgraded the PC to Windows XP.The Pastel Accounting ,after upgrading opened once then when I tried it for the second time it gave the message
Error Code 20
Record Manager Inactive
Please check your Btrieve settings
and terminanted.I tried following the instructions in their help menu but have failed.What could be the cause and what is the appropriate solution.