ClickLock is an XP-native mouse function, usually controlled on the first tab of Control Panel->Mouse:
Logitech MouseWare and a few other mouse drivers may hide this option, but it is still in effect (either enabled or disabled). To change the option, you either have to:
- Uninstall MouseWare (or the other driver that is hiding the option), change the option, then re-install MouseWare (or other driver)
- Or, change the registry setting by hand (see below)
ClickLock in Windows XP is controlled in the registry in:
HKCU\Control Panel\Desktop\UserPreferencesMask
Note that there are a lot of Windows UI preferences controlled by this registry entry. See MS TechNet for a fairly-complete list.
ClickLock is controlled by bit 24 of this mask.
To enable ClickLock, add x800000 to your current value.
So, if your current UserPreferencesMask is B0 B2 05 80, change it to B0 32 05 80 to enable ClickLock.
Do the reverse to disable ClickLock.
Also, the length of ClickLock is controlled by:
HKCU\Control Panel\Desktop\ClickLockTime
I'm not sure what the units are on this, possibly milliseconds.