outlook blocked access to the following potentially unsafe attachments. How to unblock?

In outlook, try going into Tools/Options
then go to the Security tab
then change the Zone.
You might have it set on Restricted or something.
Ive a feeling it might not make too much difference but have a try anyway.

Or ask the sender to zip the file and resend it, see if that helps

You might also want to try what Microsoft suggest http://support.microsoft.com/kb/829982

Thanks, nidhi.
The settings in outlook didn't help me, or I didn't know which to change, but changing the registry as described by microsoft did it for me.
Basically I ran regedit from the Start Menu / Run and then looked for HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\Security
There I added "Level1Remove" with the STRING Value: which has to be semicolon-delimited list of file extensions to unblock (e.g., ".URL;.MDB;.REG;.EXE;.VBS")
I added .js, because that was what gave me problems.
Beware that "10.0" depends on your outlook version, my version was 11.0.
There are also programs that do this automatically, this page refers to one, but I haven't tried it: http://www.dx21.com/HOME/ARTICLES/P2P/AR...

I realised afterwards that setting security zone wouldnt of done it. I think its more to do with html emails and that kind of stuff.

Thanks a lot for the answer, it helped me a lot.

I prefer to use specialized software to control Outlook attachment security settings.
My company bought unlimited license for all computers from AgileEra (http://oasa.agileera.com). And it works very fine.