Run regedt32 and set the HardwareHandshaking key to 0. Double-click the key, enter the value, then click OK. There is a key for each installed touchscreen.

HKEY_LOCAL_MACHINE
1. \System
1. \CurrentControlSet
1. \Services
1. \MonMouse
1. \Touchscreen0
1. \Parameters
1. HardwareHandshaking = REG_DWORD 0x 00