Sharepoint document library file type and click events

I have a sharepoint document library where users upload files.

The allitems.aspx (the standard view) doesn't show correct icon for PDF and other files. Why is it so?

Also when users click on the document it doesn't open the file. For example clicking on a PDF document doesn't open using Acrobat reader even though it is installed on the server.

I even checked the file association by going to IE->Tools->Internet options->Set programs. The PDF is associated to acrobat reader.

Is there any other place to check? Another issue is with the JPEG file. Within allitems.aspx it shows the image i开发者_开发知识库con but when I click it tries to open using IE (which is fine) but doesn't load the image.

Are there any other settings? Please suggest. thanks.