Unable to Upload Multiple Documents to Sharepoint 2007
Multiple uploading is only available for Internet Explorer (32-bit) 9 or below. For newer versions, you will need to run them in compatibility mode in order to activate this feature.
This quick fix will allow you to select many documents for upload at a time.
Internet Explorer 10: On any page, hit F12. This brings up IE10's developer mode. Click on "Browser Mode:" and change the setting to "IE 10 Compatibility". Refresh or go to the sharepoint site to upload as normal.
Internet Explorer 11: While on the sharepoint site, click the gear at the top right of IE. Choose "Compatibility View settings", the current site should already be in the textbox. Hit add, and restart Internet Explorer. Re-attempt sharepoint document upload.
Should these methods fail, contact the Central IT Service Desk or continue troubleshooting through security changes in ActiveX controls for Internet Explorer through this method: IE Gear --> Internet Options --> Security --> Custom Level