Attached is a file with 66 entries. If there are only 64 entries, tasks can be edited, indented or outdented and OpenProj will open the saved file. However, with more than 64 lines and the indents shown in the POD attached, indenting any line will make it so that OpenProj will not open the file after saving. For example, Open the file, go to line 22 (SubTask 2.2.2), indent it and save the file. Then try opening in with Win 7 64-bit.