Thanks Jason,
I have noticed that when I try to uninstall eCart to upgrade to eCart 6.0.6 and then reninstall it that I get the message :
While executing timer, the following JavaScript error occurred:
At line 139 of file xxx/xx/xxx/Adobe Dreamweaver CS5.5\Configuration\Commands\WA_uninstall2.htm:
shareMatch has no properties
Once I install 6.0.6 I don't get any more javascript errors
Could this be a problem?