VirtualBox Failed to open a session; Constructor in main failed due to a COM error (0x80004005)

I have used a virtual ubuntu machine for over half a year, but a few days ago I added a second VM (android) and a little later removed it after all. But since I did that (I believe?) My other VM won't load anymore!

Each time I try to run the first VM that I have been using for months I get the following message:

The configuration constructor in main failed due to a COM error. Check the 
release log of the VM for further details. (VERR_MAIN_CONFIG_CONSTRUCTOR_COM_ERROR).

Result Code: E_FAIL (0x80004005)
Component:  ConsoleWrap
Interface:  IConsole {872da645-4a9b-1727-bee2-5585105b9eed}

I tried cloning the VM, but that gives the same error on the clone. I checked online but there is nothing wrong with my ubuntu.vbox or .vbox-prev files... This is the log file:

VirtualBox VM 5.2.4 r119785 win.amd64 (Dec 18 2017 15:47:18) release log
00:00:02.204038 Log opened 2018-11-14T07:58:25.111291400Z
00:00:02.204039 Build Type: release
00:00:02.204042 OS Product: Windows 10
00:00:02.204044 OS Release: 10.0.17134
00:00:02.204044 OS Service Pack: 
00:00:02.320643 DMI Product Name: 80SR
00:00:02.326747 DMI Product Version: Lenovo ideapad 510-15ISK
00:00:02.326760 Host RAM: 8097MB (7.9GB) total, 3446MB (3.3GB) available
00:00:02.326763 Executable: D:\VirtualBox\VirtualBox.exe
00:00:02.326763 Process ID: 11908
00:00:02.326764 Package type: WINDOWS_64BITS_GENERIC
00:00:02.328934 Installed Extension Packs:
00:00:02.328975   None installed!
00:00:02.329980 Console: Machine state changed to 'Starting'
00:00:02.331758 Qt version: 5.6.2
00:00:02.335080 GUI: UIMediumEnumerator: Medium-enumeration finished!
00:00:02.438713 SUP: Loaded VMMR0.r0 (D:\VirtualBox\VMMR0.r0) at 0xXXXXXXXXXXXXXXXX - ModuleInit at XXXXXXXXXXXXXXXX and ModuleTerm at XXXXXXXXXXXXXXXX using the native ring-0 loader
00:00:02.438736 SUP: VMMR0EntryEx located at XXXXXXXXXXXXXXXX and VMMR0EntryFast at XXXXXXXXXXXXXXXX
00:00:02.438745 SUP: windbg> .reload /f D:\VirtualBox\VMMR0.r0=0xXXXXXXXXXXXXXXXX
00:00:02.441956 AssertLogRel F:\tinderbox\win-5.2\src\VBox\Main\src-client\ConsoleImpl2.cpp(778) int __cdecl Console::i_configConstructorInner(struct UVM *,struct VM *,class util::AutoWriteLock *): !FAILED(hrc)
00:00:02.441981 hrc=ERROR_MOD_NOT_FOUND 0x8007007E
00:00:02.568264 VMSetError: F:\tinderbox\win-5.2\src\VBox\VMM\VMMR3\VM.cpp(361) int __cdecl VMR3Create(unsigned int,const struct VMM2USERMETHODS *,void (__cdecl *)(struct UVM *,void *,int,const char *,unsigned int,const char *,const char *,char *),void *,int (__cdecl *)(struct UVM *,struct VM *,void *),void *,struct VM **,struct UVM **); rc=VERR_MAIN_CONFIG_CONSTRUCTOR_COM_ERROR
00:00:02.568309 VMSetError: The configuration constructor in main failed due to a COM error. Check the release log of the VM for further details.
00:00:02.569082 ERROR [COM]: aRC=E_FAIL (0x80004005) aIID={872da645-4a9b-1727-bee2-5585105b9eed} aComponent={ConsoleWrap} aText={The configuration constructor in main failed due to a COM error. Check the release log of the VM for further details. (VERR_MAIN_CONFIG_CONSTRUCTOR_COM_ERROR)}, preserve=false aResultDetail=0
00:00:02.570263 Console: Machine state changed to 'PoweredOff'
00:00:02.588186 Power up failed (vrc=VERR_MAIN_CONFIG_CONSTRUCTOR_COM_ERROR, rc=E_FAIL (0X80004005))
00:00:03.090209 GUI: UIMachineViewNormal::resendSizeHint: Restoring guest size-hint for screen 0 to 1440x820
00:00:03.090348 ERROR [COM]: aRC=E_ACCESSDENIED (0x80070005) aIID={76eed314-3c72-4bbb-95cf-5eb4947a4041} aComponent={DisplayWrap} aText={The console is not powered up}, preserve=false aResultDetail=0
00:00:03.091351 GUI: Aborting startup due to power up progress issue detected...

Also I can no longer edit settings of the VM. That would give me the error: "is not a valid guest OS type (VBOX_E_OBJECT_NOT_FOUND (0x80BB0001)

Is there anyone who can help me? I'm not finding useful help online anymore and I really need to use the programs installed in that VM. Thanks in advance!