I had exactly the same issue on just one machine - another 3 machines all OK.
This was the fix for the troublesome wallet. Its basically the method for manually restoring an old wallet.
1 - Back up your wallet.dat file (just copy and paste to a USB memory stick).
2 - Run the .msi file and uninstall Ultracoin
3 - Manually Delete ALL Ultracoin folders (Folders in Roaming Apps and folder under Program Files (x86)
4 - Run .msi and install a clean new wallet
5 - Sync the new wallet (it will have a zero balance)
6 - Rename the wallet.dat file in this new wallet (in Ultracoin folder which is in roaming apps folder) - name it anything but not wallet.dat i.e. zerowallet.date
7 - Paste your old backed up wallet.dat into the same folder
8 - open the Ultracoin wallet
9 - Hey presto! You will have a wallet fully functioning with your old wallet and its balance
I have no idea what the issue was (but suspect some conflict is left over in one of the old Ultracoin Folders) - and I have no idea why it worked but this is the last resort method IMO.
If you are at all unsure about performing any of the steps - probably best not to try or get someone to help you. Above all - if you have your wallet backed up (in more than one place especially a few USB memory sticks - best not to back up to online location) you cant really fail in the long run.
Good luck!
Windows V.733.1 does not work. Worked at first for two days then took an hour but now won't open at all.
