You are in the wrong forum. This is Premiere PRO and not Elements which you are using.
A moderator will probably fix this soon.
What device are you using to capture your analog video?
Most cheap devices (capture cards, Dazzle capture devices, etc.) will not produce video that is editable in Premiere Elements. You need to use a DV bridge, like the ADS Pyro AV Link, which produce DV-AVI files, as detailed in the FAQs to the right of this forum.
Also, since this is a custom-built PC, ensure that all hard drives are set up in your computer's set-up/BIOS and not just in the operating system and that all hard drives are formatted NTFS rather than FAT32 as they come from the factory. FAT32 drives have a file size limit that can choke video work.
I am using a Canopus ADVC110 bridge.
I will check BIOS and NTFS/FAT32 tonight but there is only 1 drive and I am positive it's NTFS.
It could also be a Windows process (Indexing for instance or even a Power/Sleep setting) or an automatic program (like a auto-defrag program or a Norton or McAfee antivirus app) that's interrupting your capture. If the program is interrupted even for a moment, it will break capture.
Its the Canopus ADVC110. Worked fine on my 'small' svhs tapes (30min).
My Hi8 are 90mins and I only have 1 NTFS drive.
I have basically only installed win7 pro and prel8. Dont have Norton or McAfee
or auto defrag (using MS security essentials).
I will check sleep settings tonight.