Skyrim CTDs every 15 to 20 mins

[doomcat9]

I get these stupid CTDs. Upon investigation i found this:

 

[09/09/2015 - 01:54:43PM] Error: Unable to call IsSwimming - no native object bound to the script object, or object is of incorrect type

stack:

[None].Actor.IsSwimming() - "<native>" Line ?

[Active effect 4 on <NULL actor> (00000000)].fwabilitybeeingfemale.OnUpdate() - "FWAbilityBeeingFemale.psc" Line 146

[09/09/2015 - 01:54:43PM] Warning: Assigning None to a non-object variable named "::temp21"

stack:

[Active effect 4 on <NULL actor> (00000000)].fwabilitybeeingfemale.OnUpdate() - "FWAbilityBeeingFemale.psc" Line 146

[09/09/2015 - 01:54:44PM] [CF][Framework] Didn't add active actor ["Male Frostbite Spider" [lvlpredatorscript < (00085B00)>]]; already active

[09/09/2015 - 01:54:47PM] [DLC2PillarBuilderActorScript < (050177DB)>]OnPackageStart()

[09/09/2015 - 01:54:50PM] VM is freezing...

[09/09/2015 - 01:54:50PM] VM is frozen

[09/09/2015 - 01:54:50PM] Saving game...

[09/09/2015 - 01:54:51PM] VM is thawing...

[09/09/2015 - 01:54:57PM] Error: Unable to call IsSwimming - no native object bound to the script object, or object is of incorrect type

stack:

[None].Actor.IsSwimming() - "<native>" Line ?

[Active effect 4 on <NULL actor> (00000000)].fwabilitybeeingfemale.OnUpdate() - "FWAbilityBeeingFemale.psc" Line 146

[09/09/2015 - 01:54:57PM] Warning: Assigning None to a non-object variable named "::temp21"

stack:

 

please tell me what this means and how to fix it?