An internal error occurred.

[Sunial]

In my query I use AVG function to retrieve average of a variable in ms access.
Everything was working and all of a sudden, Coldfusion Server complains that

'Error Executing Database Query.
[Macromedia][SequeLink JDBC Driver]An internal error occurred. '

When I take out the AVG function and use SUM(var) / COUNT(var) to get the
average, it stops complaining.
However, the AVG function was working fine before. Any ideas?
Thanks.