Updated Frequently asked questions (markdown)

Frequently-asked-questions.md

@@ -46,4 +46,21 @@ When these are updated, Ghidra should automatically compile them, producing ```.
 You may need to restart Ghidra to convince it to recompile.
 The documentation for our Sleigh language is at ```docs/languages/index.html```.
 There is also a useful script for debugging: ```DebugSleighInstructionParse.java```.
-Put you cursor at the start of the faulty/missing instruction and run it for a rather verbose dump as it attempts to parse the instruction.
+Put you cursor at the start of the faulty/missing instruction and run it for a rather verbose dump as it attempts to parse the instruction.
+
+### I'm getting Access Denied errors running Ghidra from a read-only installation
+
+It's likely Ghidra is trying to recompile its Sleigh files.
+If it's truly read-only, then it's not likely a user is modifying the Sleigh specs.
+Rather, it's likely the timestamps of the installation files were inadvertently updated.
+If the ```.slaspec``` or ```.sinc``` files have a later timestamp than the ```.sla``` files, Ghidra will atttempt to recompile them, writing them to the installation directory.
+If you unpacked the installation and then copied it to the read-only location, be certain the timestamps are preserved by the copy.
+If you are using an unofficial installer package, it's likely the timestamps were inadvertently modified by the packagers.
+You should be able to fix this by updating the timestamps of the ```.sla``` files.
+On Linux, try
+
+```bash
+touch `find . -name '*.sla'`
+```
+
+from the installation directory.