First for the Time Machine issue check out this document: Mac OS X 10.5.3 or later: Time Machine - "Backup volume could not be mounted" after changing network volume's or one of the documents listed here: Apple - Support - Time Machine. That problem has been discusses before but no apparent fix as far as I can tell: Re: Cannot restore iPhoto library due to "permissions".
Regarding your current library if you have the space available on your hard drive and don't aready have a backup copy of the library make a temporary, backup copy (select the library and type Command+D) and apply the two fixes below in order as needed:
Launch iPhoto with the Command+Option keys held down and rebuild the library.
Select the options identified in the screenshot.
Using iPhoto Library Manager to Rebuild Your iPhoto Library
- Download iPhoto Library Manager and launch.
- Click on the Add Library button, navigate to your Home/Pictures folder and select your iPhoto Library folder.
- Now that the library is listed in the left hand pane of iPLM, click on your library and go to the File ➙ Rebuild Library menu option
- In the next window name the new library and select the location you want it to be placed.
- Click on the Create button.
Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments but not books, calendars or slideshows. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.
If the above doesn't help you can do the following and get back all of the original files that are in the library:
Start over from scratch with new library
Start over with a new library and import the Originals (iPhoto 09 and earlier) or the Masters (iPhoto 11) folder from your original library as follows:
1. Move the existing library folder to the desktop.
2. Open the library package like this.
Click to view full size
3. Launch iPhoto and, when asked, select the option to create a new library.
4. Drag the Originals (iPhoto 09 and earlier) or the Masters (iPhoto 11) folder from the iPhoto Library on the desktop into the open iPhoto window.
Click to view full size
This will create a new library with the same Events as the original library but will not keep the metadata, albums, books slideshows and other projects.