There is a known bug with the Adobe Acrobat and Adobe Acrobat Reader version 4.0 plug-in applications for Microsoft IE. Some PDF files do not open properly. This bug was corrected by Adobe in version 5 of both Acrobat and Acrobat Reader.

If you can upgrade your system to version 5 (you will need to uninstall the old version first) then this would be the permanent solution to getting PDF files to open correctly in MS IE.

There are a number of workarounds recommended by Adobe if you are not in a position to upgrade.

Solution 1
Start Acrobat or Acrobat Reader, and then open the PDF file in the Web browser.

Solution 2
Make sure that the External Window Handler (ewh32.api) is in the Plug-ins folder. If this file is missing, reinstall Acrobat or Acrobat Reader.

The default location of the Plug-ins folder is
-- (Acrobat) Program Files/Adobe/Acrobat [version]/Acrobat
-- (Acrobat Reader) Program Files/Adobe/Acrobat [version]/Reader

Solution 3
Disable Web Browser Integration so that PDF files open directly in Acrobat or Acrobat Reader instead of within the Web browser.

To disable Web Browser Integration in Acrobat 5.0 or Acrobat Reader 5.0:
1. Open Acrobat or Acrobat Reader.
2. Choose Edit > Preferences > General.
3. Click Options in the list in the Preferences dialog box.
4. Deselect Display PDF in Browser.
5. Click OK.

To disable Web Browser Integration in Acrobat 4.x or Acrobat Reader 4.x:
1. Open Acrobat or Acrobat Reader.
2. Choose File > Preferences > General.
3. Deselect Web Browser Integration in the General Preferences dialog box.
4. Click OK.

What we have also found works (although not a perfect solution obviously):

1) Click on your back button and try the file again

2) Save the file to your hard drive and open it from the Program rather than in MS IE

3) Open a different PDF file that works in a separate browser window, and then open the file you are actually looking for.

To get the most recent version of Adobe Acrobat - click here