Header error message, very confusing situation

Question

Hi everyone!
I havent done any serious video editing so I am quite new to setting it all up. I really wanted to do a video montage of old home movies for my wedding next month. So please help! Basically I have used my canon 5d mkii to film my tv and capture some old movies (the quality is quite good actually). Some clips are very short, some are a bit longer (>45 seconds).
Once recorded, I download the .mov files onto my external hard drive (F drive). This is a western digital 1tb USB3 drive. Model number WDBPCK0010BBK-EESN. This came formatted to NTFS. My main adobe suite is installed on my 64gb ssd crucial m4 drive. I only have 4gb of free space left on this which is why i dont store media on it.
The problem starts when trying to import to adobe preimiere pro cs6. If I download the .mov files from the camera to the F drive, then go into premiere pro and click import, the smaller clips import fine but a message saying header error or corrupt file appears and it wont import the larger files (>45seconds).
This is where it gets strange (in my opinion). If I download the files from the camera to my C drive, then import to premiere pro, all the files work, even the big ones! No errors at all. Also, if I transfer the .movs from my C: drive, to my F; drive, and then import them from my F; drive into premiere pro they still work. No errors again. So it just doesnt work if they were imported from the camera to F; drive. I dont understand why :/
My scratch disks are set to F drive.
What is the difference between importing from my camera to C: drive or F: drive? Why does that effect premiere pro?
Is this a scratch disk problem?
Is this because my F drive isnt fast enough?
Is it becuase i need to transode the .mov files first? I was under the impressions this wasn't need with CS6?
I dont use a graphics card... I just use my i72600k and z68 mobo combo.
What should I do? I could afford one more new hard drive, and I wouldnt mind buying a new ssd and getting a bigger one, and swapping it with my current ssd so the new one holds the operating system and use the 64gb just for scratch files / rendering? However I am very poor right now with paying for the wedding so if there is another option that would be great.
Thanks everyone,
Craig

Answer 1

If I understood you correctly, files that wouldn't work from your F: drive yesterday suddenly started working today, even though you didn't do anything?  This indicates to me that your problems are based on speed-of-transfer issues, as well as files not being ready to be used even though they may be visible in Explorer or File Open windows.  Four clues lead me to that conclusion:
Your SSD is much faster than your external drive, so read/write operations occur in a fraction of the time.
You are only having problems with larger files (>45 mins. of video).
The File is Ready for Archiving attribute only shows up when the file is completely written, has been checked by Windows, and is made available to backup utilities.
PEK files allow Pr to draw the waveforms in the timeline, and for longer video clips this can take a few minutes. 
My suggestion to you is to start transferring files from the camera to your F: drive (the USB transfer should be OK, but it's going to be slow), and while that's going on, go get a cup of coffee.  Give all the file operations a chance to be completed by Windows before you try to import into Pr. 
Jeff
EDIT: I should add that your USB setup is a huge bottleneck.  If you think about it, the data has to go from the camera through a USB port (2.0 maybe?), out through another USB port to be written to the F: drive, then read back into the computer for playing or editing from that very same F: drive through that very same USB cable, all while the computer is still trying to write more data to the external drive.  It's like a salmon swimming upstream.