I've had citrix lanuch.ica problem (asking to download launch.ica instead of opening up the citrix) 

when my home PCs to connect to the secure Citrix gateway at work.  The solution's always the same for me:

1) Open the following URL in your browser:

http://www.citrix.com/site/ss/downloads/details.asp?downloadId=1681207&productId=186#top

2) Download & install the "XenApp Web Plugin" .msi file   (from what I've seen it doesn't matter where on your C:\ drive you install it)

3) Retry Citrix access and it should work now