每次我尝试使用 Firefox 将图像上传到媒体库时，都会弹出一个错误消息，提示“上传文件时发生错误”。检查 sitecore 日志后，我在堆栈跟踪中看到以下内容：
288 11:29:27 ERROR Application error.
Exception: System.ArgumentException
Message: Illegal characters in path.
Source: mscorlib
at System.Security.Permissions.FileIOPermission.HasIllegalCharacters(String[] str)
at System.Security.Permissions.FileIOPermission.AddPathList(FileIOPermissionAccess access, AccessControlActions control, String[] pathListOrig, Boolean checkForDuplicates, Boolean needFullPath, Boolean copyPathList)
at System.Security.Permissions.FileIOPermission.AddPathList(FileIOPermissionAccess access, String[] pathListOrig, Boolean checkForDuplicates, Boolean needFullPath, Boolean copyPathList)
at System.Security.Permissions.FileIOPermission..ctor(FileIOPermissionAccess access, String[] pathList, Boolean checkForDuplicates, Boolean needFullPath)
at System.IO.File.GetLastWriteTimeUtc(String path)
at Sitecore.Resources.Media.MediaData.get_MediaId()
at Sitecore.Resources.Media.MediaCache.CanCache(Media media, MediaOptions options)
at Sitecore.Resources.Media.MediaCache.GetStream(Media media, MediaOptions options)
at Sitecore.Resources.Media.Media.GetStream(MediaOptions options)
at Sitecore.Resources.Media.MediaRequestHandler.DoProcessRequest(HttpContext context, MediaRequest request, Media media)
at Sitecore.Resources.Media.MediaRequestHandler.DoProcessRequest(HttpContext context)
at Sitecore.Resources.Media.MediaRequestHandler.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute ()
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute ()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Heartbeat 11:30:04 WARN Memory usage exceeded the MemoryMonitor threshold.
Heartbeat 11:30:04 WARN Memory usage: 1,680,764,928
Heartbeat 11:30:04 WARN Number of suppressed logs due to the minimum time between log entries: 10
我可以看出存在某种非法字符异常，但我不知道从哪里看。这个问题的原因可能是什么，我该如何解决？是否有地方可以在 sitecore 中配置文件路径？
我正在使用 Sitecore 6.5