My way of dealing with the "big file with errors some where in it" prob.
I st 1st identify where the error(s) are...using the 'Test' command in Winrar, Winzip or whatever.
Maybe start to install the thing and note where the install fails..assuming
the installer works from begining towards end of file.
NOW
get up a good Hex edit prog that can deal with big file editing..
I use "HEXEDIT" which lives here <a href='http://www.expertcomsoft.com/' target='_blank'>http://www.expertcomsoft.com/</a>.
Cut the file up at the point just before the error use this 1st good bit
with the Resume feature of your download manager to get the next little bit added free of error ....Now edit the orginal 2nd bit of the file on the end having cut off the bad bit.
I once corrected 4 seperate errors in a 180MB RIP of GTA3 in this way
A lot of work but better than re-downloading on my then 33kb line.
U no sume time I tink it Might be easlyer to go to shop and buy the thing
....but thats not really the point is it??