We have seen an influx of issues with Office Web Apps 2013 being installed on a Non-System Drive using VMWare.
The issues have mainly been sporadic and we are working to narrow them down. Below is a prime example (with ULS entry) of the unusual behavior we are seeing:
"Microsoft Word Web App"
Sorry, there was a problem and we can't open this document. If this happens again, try opening the document in Microsoft Word."
Here is an example of what we are seeing in the ULS logs:
03/14/2014 14:02:40.53 w3wp.exe (UTMSSP01:0x1620) 0x0BB8 SharePoint Foundation General ai1wu Medium System.IO.FileNotFoundException: The system cannot find the file specified. (Exception from HRESULT: 0x80070002), StackTrace: at Microsoft.SharePoint.SPWeb.GetList(String strUrl) at Microsoft.SharePoint.SPWeb.get_SiteAssetsLibrary() at Microsoft.SharePoint.Utilities.SPWOPIHost.GetHomeUrlForFile(SPFile file, Boolean isAttachment) at Microsoft.SharePoint.SoapServer.Wopi.RunCheckFile(HttpContext context, CommonRequestData requestData, CommonResponseData responseData) at Microsoft.SharePoint.SoapServer.Wopi.ProcessRequestCore(HttpContext context, CommonRequestData requestData, CommonResponseData responseData) at Microsoft.SharePoint.SoapServer.Wopi.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) at System.Web.HttpApplication.PipelineStepManager.ResumeSteps(Exception error) at System.Web.HttpApplication.BeginProcessRequestNotification(HttpContext context, AsyncCallback cb) at System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) at System.Web.Hosting.PipelineRuntime.ProcessRequestNotificationHelper(IntPtr rootedObjectsPointer, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags) at System.Web.Hosting.PipelineRuntime.ProcessRequestNotification(IntPtr rootedObjectsPointer, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags) at System.Web.Hosting.UnsafeIISMethods.MgdIndicateCompletion(IntPtr pHandler, RequestNotificationStatus& notificationStatus) at System.Web.Hosting.UnsafeIISMethods.MgdIndicateCompletion(IntPtr pHandler, RequestNotificationStatus& notificationStatus) at System.Web.Hosting.PipelineRuntime.ProcessRequestNotificationHelper(IntPtr rootedObjectsPointer, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags) at System.Web.Hosting.PipelineRuntime.ProcessRequestNotification(IntPtr rootedObjectsPointer, IntPtr nativeRequestContext, IntPtr moduleData, Int32 flags) 33bd837e-42a2-4d46-89cf-e992045d4964
The Resolution is to uninstall Office Web Apps 2013, re-install (on the C: drive), apply updates and rebuild the farm.
At the moment we are trying to isolate a root cause for why exactly this is happening (dynamic attach of disk in VMWare, maybe). But for now, if you want OWA 2013 to work using VMWare, make sure it is installed on the C: drive.