SharePoint: When you download a file in Internet Explorer 7, the space character in the file name is changed to a underscore

Issue: whenever user is trying to download a file form SharePoint site its Spaces gets replaced with the special character underscore (-).

Background: A user had a long file names with spaces and when he downloads the file. The spaces gets replaced with underscore _. For example: file name “Amardeep SharePoint Public.ppt” will be replaced with “Amardeep_SharePoint_Public.ppt”.

Troubleshooting:

-          Tried every possible solution to check on this issue such as uploading multiple file with different extensions.

-          Tried files with short names and long names.

-          Tried repairing the office package.

-          It was showing issue on most of the machines, however on the machine where we had IE 8 and above this working as expected.

-          It was more of an issue with the machine where we have IE 7 and was not upgraded yet.

-          If this is the case then there should be a justification, some publication available from Microsoft.

-          Showing some more curiosity had led me to the resolution of the issue.

Resolution:

There was hotfix released by MS and it’s a known issue with IE7 only.

Link to obtain Hotfix is : http://support.microsoft.com/kb/952730

You can also have your IE upgraded to next version to have this issue resolved.

TechNet Wiki 
http://social.technet.microsoft.com/wiki/contents/articles/22676.sharepoint-when-you-download-a-file-in-internet-explorer-7-the-space-character-in-the-file-name-is-changed-to-a-underscore.aspx 

Applies to: IE 7, SharePoint 2007 and SharePoint Server 2010.