*** Update ***
For this customer, the problem turned out to be McAfee Total Protection which was seriously interferring with ClinicOffice. Once he disabled McAfee, performance increased massively.
At present, it seems to be only McAfee which has this problem and we haven’t had reports of any other virus scanners with this issue.
Here at Pioneer Software, we use AVG Anti-Virus.
Here’s is a useful link to a “Top 10” site which compares the latest Anti-Virus software :-
For a FREE anti-virus solution, we recommend the AVG Free Edition, which actually scores better in many reviews than most commercial products. You can download it from here :-
Hope this helps!