New Post: Install Error 80070643

We just implementet the Newest Flash Player PlugIns into WPP and WSUS. Some Clients have problems with the instllations of the packages and some not.
Here are the some entries from the Windows Update Log:
2016-04-13 14:47:11:624 1116 1af8 Report REPORT EVENT: {EA9CB91B-04B9-444B-8ADA-DCB5A46A3925} 2016-04-13 14:46:43:035+0200 1 181 101 {5AA1188A-9903-4644-AF95-19CD9BC80A6B} 1 0 AutomaticUpdates Success Content Install Installation Started: Windows successfully started the following update: Adobe Flash Player 21 NPAPI
2016-04-13 14:47:11:624 1116 1af8 Report REPORT EVENT: {1D536A08-0FEF-4C37-B5DA-CC3618F625DB} 2016-04-13 14:46:43:790+0200 1 182 101 {5AA1188A-9903-4644-AF95-19CD9BC80A6B} 1 80070643 AutomaticUpdates Failure Content Install Installation Failure: Windows failed to install the following update with error 0x80070643: Adobe Flash Player 21 NPAPI.
2016-04-13 14:47:11:624 1116 1af8 Report REPORT EVENT: {FE0F30C8-8021-45E9-8C96-7C917927D17A} 2016-04-13 14:46:43:792+0200 1 181 101 {833E96C4-D6DC-466A-BEC9-1B7EC73C66D8} 1 0 AutomaticUpdates Success Content Install Installation Started: Windows successfully started the following update: Adobe Flash Player 21 ActiveX
2016-04-13 14:47:11:624 1116 1af8 Report REPORT EVENT: {A4F14476-DBFE-47AC-982B-C40F1331B9BB} 2016-04-13 14:46:44:455+0200 1 182 101 {833E96C4-D6DC-466A-BEC9-1B7EC73C66D8} 1 80070643 AutomaticUpdates Failure Content Install Installation Failure: Windows failed to install the following update with error 0x80070643: Adobe Flash Player 21 ActiveX.

We also tried first to uninstall the existing old Flash Player Version and install then the packages, but the result is the same.