You might read the troubleshooting thread, I made a copy and paste
The latest version of Liquid is 7.2 build 4296. You can download the full installer or the upgrade patch here. The full installer requires your 7.x serial number but can be installed on a clean install of XP without installing any prior versions. Please read the upgrade information the link takes you to very carefully and make sure you download the correct item (full or patch) for your upgrade situation.
If you have problems installing Liquid because it cannot verify your original Liquid disk, download this patch.
If you have issues because you are upgrading from programs like Adobe Premiere and do not have a Liquid disc to verify with, this has been reported to work using the above patch:
Begin installing the full upgrade. Cancel the install when you are asked for the CD.
Then run the patch.
Finally run the Setup 7.2 again.