What is your operating system?
What is your Reader version?
What is the full 1500 error message?
cannot install the update. please run adobe reader repair.
Open Adobe Reader: Help | Repair Adobe Reader Installation.
If that does not fix the problem, open Add/Remove Programs in Control Panel, then uninstall your current Reader.
If that does not work either, use the Windows Installer Cleanup Utility to remove Adobe Reader.
Now reinstall Adobe Reader 9.3 with http://ardownload.adobe.com/pub/adobe/reader/win/9.x/9.3/enu/AdbeRdr930_en_US.exe
Repair from Control/Panel | Add Remove Programs does a more comprehensive repair, you may want to try that.
I got this several weeks back. I uninstalled Adobe Reader and reinstalled it. Then, the update came through several days later, and was succesful.