Hi,
The VM1.1.xx version of Slider doesn't use jQuery but uses MooTool instead.
Since it is an old extension as of today, the problem must be caused because of the new MooTool version. MooTool should be lower than 1.3. Because Fx.Style is used to run the animation, it should be replaced by Fx.Morph.
Can you provide me your FTP account to This email address is being protected from spambots. You need JavaScript enabled to view it. and let me try to do it?
Regards.
Support and Development