my friend has exacltly the same problem as OP. i'm acting like his tech support here.
the popup appears and installation quits. i just tried to install his game to my computer to see if it's a computer/DVD drive related issue and got the same popup. that's why i'm posting this right now. the game is EFLC PC DVD version.
@mkey82: your search suggestion doesn't give any results. if you search for "GTAIV_DynamicEFLC" you get only my post and OP's post as result.
edit: sorry, i searched again and found that another post with your suggestion. i'll try that and report back.
edit2: it could not copy data2.cab file. seems like he needs to get new set of DVDs
This post has been edited by arpadarpa on Thursday, Mar 8 2012, 12:19