It's a contact syncing issue which I'm guessing you already know. This has been a bug in Android for 4 or 5 years. The same thing happened to me a couple of years back, in your case for whatever reason, Skype was the straw that broke the camel's back.

Most of the "easy fixes" you'll find (clearing data, turning sync off and back on again, etc, etc,) across the web won't work. They're aren't addressing what, 9 times out of 10 is the problem. There's a value somewhere in one of your contacts that caused Skype to freak out and take the rest of the ship down with it. It's not fun, and depending on how many contacts you have, it might take some time, but this is what worked for me -takes deeeeeeeeep breath-

Before you begin:

Turn off sync in every app your contacts are synced across. This would include going to Settings > Accounts & Sync and un-ticking "Auto Sync" and "Background Data" and going into your phone's Contacts app, Menu > Settings > Accounts & Sync, un-tick "Auto Sync" (and Background Data if it is there too, I don't use KitKat or Lollipop, sorry)

Step One - Export Your Contacts

If your phone contacts are the same as your Google contacts or if your G3 is running Lollipop (which rolls your phone contacts into your Google Contacts as I understand it), this makes things a bit easier. I apologize if you already know how to do this.

• Browse to Google.Com/Contacts. You'll probably get the new Contacts "Preview" which, for us, is kind of a pain in the ass.
  
• On the left side menu, click "More" and "Export".
  
• You'll get a dialog box asking you if you want to go to "Old Contacts", click "Go To Old Contacts"
  
• In "Old Contacts" click "More" in the top center of your screen, and "Export"
  
• In the dialog box that pops up, tick "All Contacts", the "Google CSV" radio button (should be default) and click "Export"
  
• Keep track of where the resulting CSV file downloads to or Save As if prompted.

If Google Contacts won't work for you or if you'd prefer to to export your phone's contacts, use an app such as Contacts / SMS /LOG CSV Export and export your contacts to a CSV file using the app.

The app I linked above will give your the option to E-Mail your contacts CSV, otherwise you'll have to transfer it to your computer via USB or whatever your preferred method is. E-Mailing from the app is obviously a lot easier.

Step Two - aka - The Shitty Part

I promise you, this will feel kind of good while you're doing it.

• Open up your contacts CSV file in Excel (or Open/Libre Office/Google Sheets, any spreadsheet program).
  
• Clean your contacts.
  
  • Any fields that have "strange" data - ie - anything that's not an alphanumeric character, delete it
    
  • You'll probably come across a bunch of fields that have notes or other data you no longer need. Delete that too.
    

The goal here is to have a pristine contacts CSV file. Names, phone numbers, e-mail addresses and whatever other data is absolutely necessary

Step Three - Wipe

If your contacts CSV came from Google Contacts:

• Open Google.Com/Contacts back up in your web browser.
  
• If the new wonderful Contacts preview pops up again, click Import or Export on the left hand side, and Go To Old Contacts in the dialog box that pops up.
  
• Once back in "Old Contacts", click the Select All box at the top of your contacts list, click More and Delete Contacts. If you have a lot of contacts, you'll have to repeat this until they're all gone.
  

If your contacts CSV came from your phone contacts:

I'm reading this for the G3 specifically. If you are running KitKat, you can do this. If you're on Lollipop, all of your contacts have been rolled into your Google Contacts as I mentioned earlier.

• Go to Settings > More > Application Manager
  
• Swipe right to left until you're on the "All" screen
  
• Scroll down to Contacts Storage and Clear Data
  
• Open your phone's Contacts app, tape Menu, Delete, tap Select All and tap Delete again
  

IMPORTANT NOTE If you have contacts saved to your SIM card, you will need to manually delete those. Double check this just to be safe before moving on.

Step Four - Import

For Google Contacts :

Hopefully you've still got "Old Contacts" open in your web browser.

• Click More, Import, locate your clean CSV, select and import it.
  

For Phone Contacts...it's a giant fucking pain in the ass. To save myself the typing, I'll just hope you went the Google Contacts route.

Last Step - Re-Sync

Once your clean contacts are loaded up, go through Android Settings and turn Auto Sync and Background Data back on and in your apps, if needed. This should sync your clean contacts across your apps.

This should (god, I hope) resolve the issue and prevent it from occurring again in the future. If it doesn't work, well then I just typed out all of this shit for no reason. I'll drink a beer and get over it. Maybe it will help someone else in the future. .