The reason your URL is being rewritten to file///K:/AmberCRO%20SOP/2011-07-05/SOP-SOP-3.0.pdf
is because you specified http://file://
The http://
at the beginning is the protocol being used, and your browser is stripping out the second colon (:) because it is invalid.
Note
If you link to something like
<a href="file:///K:/yourfile.pdf">yourfile.pdf</a>
The above represents a link to a file called k:/yourfile.pdf
on the k: drive on the machine on which you are viewing the URL.
You can do this, for example the below creates a link to C:\temp\test.pdf
<a href="file:///C:/Temp/test.pdf">test.pdf</a>
By specifying file:// you are indicating that this is a local resource. This resource is NOT on the internet.
Most people do not have a K:/ drive.
But, if this is what you are trying to achieve, that's fine, but this is not how a "typical" link on a web page works, and you shouldn't being doing this unless everyone who is going to access your link has access to the (same?) K:/drive (this might be the case with a shared network drive).
You could try
<a href="file:///K:/AmberCRO-SOP/2011-07-05/SOP-SOP-3.0.pdf">test.pdf</a>
<a href="AmberCRO-SOP/2011-07-05/SOP-SOP-3.0.pdf">test.pdf</a>
<a href="2011-07-05/SOP-SOP-3.0.pdf">test.pdf</a>
Note that http://file:///K:/AmberCRO%20SOP/2011-07-05/SOP-SOP-3.0.pdf
is a malformed