Adblocker Plus not working with Trend Micro Titanium

I just downloaded Trend Micro Titanium as my Norton 360 was expiring. I'm running XP Pro and Firefox. I had been using Adblocker, but it disappeared during the install of Titanium. I've re-downloaded Firefox today, thinking something was wrong there, but still can't download Adblocker again. It keeps saying error code 203.

I've really liked adblocker, but I've got ads slowing down things now. Any ideas??

 

Thanks for your suggestion. However, I uninstalled Firefox last night and shut the computer off. Today, I re-downloaded Firefox and then was able to install Adblocker Plus from the web without any errors. Everything is good!!