Cost is Adjusted field

Cost is Adjusted field in Item Card and Production Order Line will be updated if cost has been adjusted for the particular item when Adjust Cost - Item Entries is runned.

Automatic Cost Adjustment

Instead of running the Adjust Cost - Item Entries batch job manually, you can set Navision to automatically adjust cost every time you post inventory transaction. This can be done by:
1) Open Intentory Setup from Warehouse --> Setup --> Inventory Setup.
2) Set the Automatic Cost Adjustment to Always.

Adjust Cost - Item Entries run into endless loop in Navision 4.0 and 5.0

The Ajust Cost - Item Entries run into endless loop and the Adjmt. Level field keep increasing. This problem can occurs to Navision 4.0 and 5.0.The easiest thing you can check is to Open your Item Card. Press F5 to open the Item List form. Scroll to the first record to check whether you have an item witn blank No. or not. If you found a record with blank No. field, you can safely delete this record. You cannot create an Item record with blank No. but when you use Dataport to import the item, blank No. field is possible.

If the above information cannot help you, probably you have other more headache problem in your Navision. Below are some useful forum posts that may help you but I have no luck to stop the endless loop after trying the methods suggested:
1) Mibuso - adjust Cost - by Item
2) Mibuso - adj. Cost Item entries is too slow

Table 5804 - Avg. Cost Adjmt. Entry Point

Entries to be adjusted will be temporarily stored in this table. The entries in this table will be deleted after you run Adjust Cost - Item Entries batch job. So, if you want to check whether you have any entries need to be adjusted or not, you can check this table. If you find record in this table, means you have records need to be adjusted.

"Cost is Adjusted" field in Item table

The Cost is Adjusted field in Item table is a boolean field indicating the cost of the item has been adjusted or not. Whenever we post a purchase order, the Cost is Adjusted field will set to No. The status will set to Yes after we run adjust cost.