Q: problems with OS X Lion. I upgraded and now my macbook pro has been crashing...

How much RAM do you have?

Try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work.

Isolating an issue by using another user account

If the problem is still there, try booting into the Safe Mode.  Shut down the computer and then power it back up. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the grey Apple icon and a progress bar appear. The boot up is significantly slower than normal.

Safe Mode

Safe Mode - About

General information.

Isolating issues in Mac OS X

Permissions Troubleshooting

Step by Step to Fix Your Mac

What exactly happens when it crashes? Error message?

If you have more than one user account, you must be logged in as an administrator to carry out these instructions.

Launch the Console application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad. Click Utilities, then Console in the icon grid.

Select the most recent panic log under the heading System Diagnostic Reports on the left. If you don't see that heading, select  

View ▹ Show Log List
   
from the menu bar. Post the entire contents of the panic report — the text, please, not a screenshot. In the interest of privacy, I suggest you edit out the “Anonymous UUID,” a long string of letters, numbers, and dashes in the header and body of the report, if it’s present (it may not be.) Please don't post shutdownStall, spin, or hang reports.

So that I can try to find out why your machine is crashing. If you prefer not to provide that information, I can't help at all. In that case, make a "Genius" appointment at an Apple Store.

Restart normally.

also what is it you suggest i edit out...?

I believe I answered that question in my first message. You're obviously uncomfortable about posting the information, which is understandable. I'll let someone else help you with your problem. Good luck.