I believe it is a problem with your system, not the software.
Which operating system are you running? XP Pro/Home?
Which site are you playing on?
How many tables? Does it do this with 1 or 2 tables?
Tell us a little about your system: CPU speed, Amount of RAM installed.
(Start/ Control Panel / double click system: )
Thanks Monk
How many processes are currently running on your system?
When was the last time you did an antivirus scan?
Answer those and we may get somewhere.