I have been experiencing this problem since 9.04 beta on a Dell d600 laptop. it's the touchpad driver seemingly, as there is no problem when i use a logitech vx nano wireless mouse, however, when using the touchpad, the left button click will quite often get stuck down (the button up notification gets lost or ignored) I can only assume this is in the synaptics driver as the problem is not there in Win XP. it is also not a purely a ubuntu issue, as I have also tried the latest fedora FC13 live disc and the issue remains there too.

over the past year i have seen a lot of posts regarding this issue, and no clear solutions... I do hope this can be resolved as it's a fairly major inconvenience that this laptop can't really be used with linux anymore without an external mouse, and once XP is not supported with security updates, i doubt it will run Win 7 very well....