Try upgrading to Windows 10 and then installing http://devcoin.org/wallet/Devcoin-1.0.16-w32.zip.

Also backup your wallet.dat

I haven't used those win 7 or 8.1 for years. I wouldn't be able to advise you about deleting things in the roaming folder for "devcoin" but I would copy you wallet.dat folder on a usb stick so as to replace the new installation if you choose to go the route by deleting the App Data > Roaming > devcoin folder then putting your old wallet.dat into the new one after you install, run the new installation, shut down the wallet, move the old wallet.dat into the devcoin folder, and then restart it. That method has also helped me sync but again I don't recommend it because I don't know what your computer is like and I am not a dev team member.