Repairing the corrupted archives

Well the title is self explanatory.
I got a movie from movies section.
6 parts in all.
i tried to extract it in usual fashion. but it gave error
! C:\Escape\The.Great.Escape.1963.DVDRip.x264.part4.rar: Packed data CRC failed in The.Great.Escape.1963.DVDRip.x264.mkv. The volume is corrupt
! C:\Escape\The.Great.Escape.1963.DVDRip.x264.part6.rar: CRC failed in The.Great.Escape.1963.DVDRip.x264.mkv. The file is corrupt

This happens sometimes. i think i better find solution for this error, instead of getting the whole files redownloaded.
i am wondering is there any tool that can really help me.
I goggled & got lots of results. m gonna do some more research. but in meanwhile, if any one knows any efficient tool?
any help really appreciated.
Edit
I was able to extract the single movie file using the RAR Recovery Toolbox. i just selected the final 6 th part & analyzed it with this s/w. then proceeded as per instructions. first scanning of the rar (47MB) tool nearly 5 mins & same time for repairing. But it extracted the whole movie for me in single folder unded name
The.Great.Escape.1963.DVDRip.x264.part6_rar_repaired

The reason for recovery is:-
RAR files are a common way of compressing and breaking up larger files for easier transmission. However, one danger of a RAR file is that it breaks up the larger file into many smaller pieces. If one of those pieces becomes corrupt, it can make it impossible to open the overall file. Most RAR repair programs work to open the corrupted part and extract as many of the files as they can out of it, which hopefully will be enough to make the rest of the archive functional.
Answer #1
You can’t really repair it as it’s incomplete or corrupt,You can extract
ignoring this but the file will not be 100% playable so not worth it.
What you should do is figure out what is causing these corruptions,The most
common reasons are:
1. Bad router,Try hooking up your PC directly to the modem.
2. Bad download manager,Try a different one.
3. Bad RAM,Test it with memtest,Follow this guide:
http://www.google.com?p=34650602#34650602
4. Bad hard drive,Each manufacturer have it’s own diagnostic tool,I would
need to know your HDD brand in order to provide links,If unsure
open up device manager by going to start>run (or pressing winkey+r)
type devmgmt.msc and hit enter,Expand “Disk Drives” and tell me
what’s listed in there.
Answer #2
@
thanks a lot for neat answer.
but i guess this is not a regular problem for me (edited the post for same).
other downloads are working for me fine. such things happens once in a while. say after every 20-30 downloads
1. Bad router,Try hooking up your PC directly to the modem.
i have a only have modem.
my rams is fine.
no problem with HDD either.
& i use IDM, which is quite good.
Answer #3
So you think you know everything huh? Good luck to ya.
I can’t believe i wasted my time on you. Seriously dude
for next time,If you’re not genuinely interested in getting
help just don’t ask.
Answer #4
@
take it easy .
what did i said. i don’t think i said anything that offended u.
in fact look at my first line.
thanks a lot for neat answer.
Jesus man y the hell r u so serious. is telling u the reasons provided by u are not the reason for my problem, is wrong?
Answer #5
You were being arrogant thinking you know better,You automatically
ruled out everything i suggested without even looking into it,That what smiling
me off,You asked for help,You got it but didn’t want it.
Answer #6
Yeah how could you say my rams is fine.
without actually checking it with anything and why do you think having IDM is good enough why couldnt it be a corrupt installation even though it might have small corruption Before you reply about anything, you should give a reason for everything you are saying or atleast try and use the suggestion we give you