Did you update your client using AutoUpdater? It's located at your InfinityMu folder then run it as Admin. It will update all the new files for the new updates.
Please Disable your Antivirus & Firewall (Or just add our main.exe to your safe list). And run the AutoUpdateTool.exe as Admin, the problem should be fixed with that. If the problem still there please contact me at skype vpsp.1805