Curtis,For ArcHydro 2.1 and 2.0 where ApFramework is bundled with ArcHydro the GUID Product Code for silent uninstall should be:msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb
For ArcHydro 1.4 ApFramework had its own Product Code, while ArcHydro used the same Product Code as in 2.1 and 2.0. So, you'd need to run two.msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb
msiexec.exe /x {58B1A257-249D-4852-854C-3957088BDE2D} /qb
Make it /qn if you really want it silent -- no user interface, for GPO or MSSCCM scripting. Suggest that following a "silent" uninstall, you follow up with a run of the ESRI.APWR.ApRegWork.exe registry cleaner from the ApRegwork Utility folder on the ESRI_RiverHydraulics ftp site. At least a couple of times until until you know that the Microsoft installer is really cleaning everything related out of the Registry.Let us know if it all works.Stuart=-=-=P.S. Below are the Installer Package IDs and Prduct Codes that I had available. I don't have installer packages for the earlier 1.3 and 1.4 products handy to check Product Codes against, but could probably dig them out if needed.ArcHydro 2.1 & ApFramework2.1.0.91 -- {BC962DAD-C5BA-4AE9-BA40-56834D395BE1} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.43 -- {3093608A-4517-4D08-8866-5E6EAD4E1618} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.40 -- {46370555-D6A3-45F4-B267-399E55B9A6CA} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.32 -- {6F8D0A9D-E18D-49CF-80AA-09C8CA9AC557} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.27 -- {8C0989C3-A1AA-43E0-AFFB-DDE1CD9B4791} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.22 -- {E9AB51B2-5596-4CE0-8B9F-8D8085D1982E} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.19 -- {79918C94-8E10-4715-8E43-43CE9BF5BE73} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.1.0.1 -- {385905AA-59AC-4082-B104-88D7D3190362} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb=-=-=ArcHydro 2.0 & ApFramework2.0.1.133 -- {4A528FE9-44A4-4FB1-ADDA-125761FDA66F} (Final 2.0, 2011-10-10) msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.131 -- {C4A909B2-5452-40CC-819E-6AA23AC9E998} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.117 -- {3C07041C-21CB-459D-A2F1-39B7E7505E3B} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.102 -- {719FF312-0F6F-4A4F-BE34-76D68458668F} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.88 -- {050683D1-4238-44C2-AD60-0CCE5F7FDA5A} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.78 -- {757B18E9-6F3D-44B7-A512-566CAF6F8EB6} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.47 -- {43219135-F5FE-4ED0-8235-1E33007094FA} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.31 -- {CFED3F92-0F13-4E69-A8DE-76CA71E88102} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.30 -- {F36525F7-7DF3-415E-A174-14B45F25B7DE} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.15 -- {32605F23-E5B3-46F7-978F-6588C31C0AF9} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.1.7 -- {7DDB2E95-9B8F-4F20-920D-AE33F3C1ED4D} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.0.66 -- {077B8E71-7338-4109-AE8F-39450D6F4A70} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb2.0.0.40 -- {EAD23E6B-7620-4B9D-AFF2-8B79FC024504} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb=-=-=ArcHydro 1.4 & ApFramework 3.11.4.0.256 -- {584E49B6-FC78-46EC-A623-4B8ECA639CAE} msiexec.exe /x {777B898F-BB2C-4A7E-8FD9-A7E251C14E9D} /qb3.1.0.103 -- {B0CF4C6E-FFE9-4E9B-B082-0B5656B66E2C} msiexec.exe /x {58B1A257-249D-4852-854C-3957088BDE2D} /qb