Userpath must be an absolute path error

while trying to execute the matlab program through php commands i get the following error.

Unable to locate a personal folder for $documents\MATLAB
userpath must be an absolute path and must exist on disk.
Exception in thread "FileDecorationCache request queue" java.lang.RuntimeException: java.io.IOException: Could not get shell folder ID list
  at sun.awt.shell.Win32ShellFolderManager2$ComInvoker.invoke(Unknown Source)
  at sun.awt.shell.Win32ShellFolder2.getFileSystemPath(Unknown Source)
  at sun.awt.shell.Win32ShellFolder2.composePathForCsidl(Unknown Source)
  at sun.awt.shell.Win32ShellFolder2.<init>(Unknown Source)
  at sun.awt.shell.Win32ShellFolderManager2.getDesktop(Unknown Source)
  at sun.awt.shell.Win32ShellFolderManager2.createShellFolder(Unknown Source)
  at sun.awt.shell.ShellFolder.getShellFolder(Unknown Source)
  at com.mathworks.jmi.MLFileIconUtils.getNativeFileIcon(MLFileIconUtils.java:235)
  at com.mathworks.jmi.MLFileIconUtils.getFileIcon(MLFileIconUtils.java:102)
  at com.mathworks.mlwidgets.explorer.extensions.basic.DefaultFileInfoProvider$1.run(DefaultFileInfoProvider.java:64)
  at com.mathworks.mlwidgets.explorer.model.FileDecorationModel$3$1.run(FileDecorationModel.java:344)
  at com.mathworks.util.RequestQueue.execute(RequestQueue.java:105)
  at com.mathworks.util.RequestQueue.access$000(RequestQueue.java:22)
  at com.mathworks.util.RequestQueue$2.run(RequestQueue.java:75)
  at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: Could not get shell folder ID list
  at sun.awt.shell.Win32ShellFolder2.getFileSystemPath0(Native Method)
  at sun.awt.shell.Win32ShellFolder2.access$900(Unknown Source)
  at sun.awt.shell.Win32ShellFolder2$8.call(Unknown Source)
  at sun.awt.shell.Win32ShellFolder2$8.call(Unknown Source)
  at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
  at java.util.concurrent.FutureTask.run(Unknown Source)
  at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
  at sun.awt.shell.Win32ShellFolderManager2$ComInvoker$3.run(Unknown Source)
  ... 1 more
{Undefined function 'computeSIFT' for input arguments of
type 'char'.
} 
how do i solve this problem?changing the userpath using userpath(newpath) followed by savepath did not solve the problem.