This problem can occur if the Liveupdate engine encounters a problem. To resolve this you update the Liveupdate engine manually. Please follow these instructions:
1. Click here to download the update
2. When prompted Click on Save
3. Right-click on the file and select RUN AS ADMINISTRATOR
4. Follow the onscreen instructions to install the update
5. Once the update has completed launch Expert PDF 8. You will be prompted that a product update is available.
6. Click on INSTALL
7. If any errors appear click on OK to accept them. The update will then install.
You will now be able to use Expert PDF.