Hi,

Please try to delete the files after restarting the computer. The files may also disappear on their own after restarting. This may happen because Avast had locked the file for scanning while Firefox had moved it to the original name after downloading. The .part is a temporary placeholder file while downloading.

Hi,

Thanks for your reply. I forgot to mention that I had restarted the computer several times and I still couldn't delete the files.

I let malwarebytes scanned my computer last night and it detected nothing, so I believe it's not related to virus or malware.

Thanks a lot again for your time.

Are Open and Open Containing Folder grayed in the right-click context menu in the Download Manager?

You can do a disk check with the chkdsk.exe program.
If you run the chkdsk.exe program from a cmd.exe Command window then you can read the response from the chkdsk.exe program.

Open a cmd.exe window:
Start > Run: cmd.exe <press Enter>
At the command prompt (>) type or Copy&Paste: chkdsk.exe /f /r <press Enter> (put a space before /f and /r)
If you get something like: Would you like to schedule this volume to be checked the next time the system restarts? y/n then answer the question with "Y" and close all programs and reboot the computer.

Hi cor-el,

Thanks for your reply. There is nothing in firefox download manager. In fact, when the downloads were done, the list cleared itself (as usual).

I tried your method and performed a disk check. After the program was done, there was no bad sector, so it seems like my notebook is fine. So I dunno what to do with those weird part files anymore. I just moved the folder to My Documents. As long as it causes no harm to the computer, I think that shall be fine (sigh.. lol).

Thanks you both again for the support. I'm glad that someone answered my questions immediately after I posted the problem.  :D.